Readme for last release adapted

Set use_condenser to True
Add unit test for hash_op

Blockchain
* raw_ops added to stream, when set to True stream() produces the same output as the old Blockchain.ops()
Unit tests
* Add unit tests for testing raw_ops

Account
* Parameter accuracy renamed to stop_diff
* Doku for estimate_virtual_op_num improved
* Several improvements and fixes for estimate_virtual_op_num
CLI
* rewards command improved and more paramter added
Comments
* Assure Amount class for all amounts
* is_pending improved
Doku
* tutorial about showing all posts of an account added
Unit tests
* test_account, test_cli and test_comment improved

Certain transaction could not be verified, as the recover parameter in verify_message from ecdasig was wrong.
Signed_Transaction.verify() iterates now always through all 4 cases and returns all found key combination.

Unit test added for this case.

Account
* print_info improved (Last Vote added)
* entryId changed to start_entry_id in get_feed, get_blog_entries and get_blog
*rpc.get_account_history moved to _get_account_history
* estimate_account_op added, can be used to fastly get account op numbers from dates or block nums
* history and history_reverse uses estimate_account_op
Exception
* KeyNotFound removed
Memo
* raises MissingKeyError instead of KeyNotFound
Price
* small improvement
Steem
* __repr__ added
Transactionbuilder
* get_potential_signatures, get_transaction_hex and get_required_signatures added
* raises MissingKeyError instead of KeyNotFound
VotesObject
* __contains__, __str__ and __repr__ added
Wallet
* raises MissingKeyError instead of KeyNotFound
Witness
* __contains__, __str__ and __repr__ added to WitnessObject
Steemnoderpc
* small improvements
Operationsid
* producer_reward added
Unit tests
* new function added and tests adapted to changes

Blockchainobject
* auto_clean function added. Everytime a new item is stored into the cache, all expired elements are removed.
* The __contains__ function sets now data ot None, when the date is expired, in order to reduce memory consumption
CLI
* threading for pingnode added. with --threading, all nodes are tested simultanously.
Steemnoderpc
* Error count and exception improved when only one node is available
Graphenerpc
* regests.session is stored as signelton
* requests_retry_session removed
* shared_session_instance and set_session_instance is used to get and set the global request.session object
* create_ws_instance added; A websocket is created everytime and the singleton is removed
* error_cnt and num_retries_call handling improved
RpcUtils
* sleep_and_check_retries improved
Examples
* benchmark_node2 uses threads (one thread for each node)
* memory_profiler2 added to check memory consumption for creating multiple account objects
Unit tests
* test for objectcache improved

Unit tests fixed

Account
* Examples and Dokumentation improved
Amount
* Example improved
Asciichart
* Examples improved
Blockchain
* examples improved
Discussions
* Doku improved
Market
* Examples and Doku improved
Price
* Examples improved
* Missing steem_instance fixed
Steem
* Example code fixed
Graphenerpc
* Example improved

Account
* Example forget SimilarAccountNames  added
* Example for history and history_reverse improved
Amount
* Example is tested with doctest
Block
* Example is tested with doctest
Price
* Fix example
Profile
* Fix example
Steem
* Example is tested by doctest
Transactionbuilder
* Example is tested by doctest
Vote
* datetime.now() changed to datetime.utcnow()
* Example is tested by doctest
Witness
* datetime.now() changed to datetime.utcnow()
* Example is tested by doctest
Docs
* Installation instruction improved
* Quickstart created
* Discord channel added to support

Fix wallet unlock when using keyring

steem
* add option use_condenser
steemnoderpc
* refactoring
Graphenerpc
* condenser_api calls shen use_condenser=True is set.
unit tests
* test_comment and test_discussion uses 19.4 nodes now

Memo
* make prefix changeble
Transationbuilder
* sign() return the signed struct now
Graphenerpc
* Session are used for requests
* Singleton for websocket instance added
* Both measures reduce ram consumption when more than one Steem object is created.
Add missing scrypt package to dependency

Account
* get_bandwidth refactored
* get_account_bandwidth added
Cli
* power added for showing vote power and bandwidth
Steem
* Improvements and refactoring for get_config, get_network, get_hardfork_properties, get_current_median_history, get_reward_funds, get_feed_history, get_reserve_ratio and get_dynamic_global_properties
Steemnoderpc
* get_network moved to graphenerpc
Chains
* removed to beemgraphenebase/chains.py
Unit tests
* add unit test for power for cli
* golos test reduced
*

cli
* Add price prediction for buy and sell of cli
steemnoderpc
* refactoring
Exceptions
* CallRetriesReached added
unit tests
* tests for test_cli added

account
* set_withdraw_vesting_route added
cli
 * powerdownroute, convert and interest added
steemnoderpc
* error messages improved
* _check_api_name added
* ApiNotSupported when Api is not supported by node but exists
graphenerpc
* error messages improved
rpcutils
* error messages in sleep_and_check_retries improved
unit tests
* new function added

Graphenerpc
* some refafctoring
Steemnoderpc
* fix next_node_on_empty_reply

Steem
* max_vote_denom is corrected and calculated as in steemit/steem
beemgrapheneapi
* handling of empty replies added

Graphenerpc
* Handling for Connectionerror for request posts added
* Each node has its own error count now
benchmark_nodes2 added

Steem
* vests_to_sbd and vests_to_rshares added
* rshares_to_vote_pct let you calculate how many voting percentage are needed  to vote with a desired rshares amount
* app can be set for post, when not set, it is set to beem/version
* Doku improved
Transactionbuilder
* Doku improved
* proposer from __ini__ removed, as it had no function
* _is_signed and _is_constructed fixed
* reconstruct_tx added to sign and addSigningInformation, when set to False, previous signatures are not deleted anymore
* KeyNotFound exception handled
Wallet
* KeyNotFound exception handled, when more than one key_auths are available
Graphenerpc
* version string set to user-agent
Publickey
* Doku improved
Unit tests
test_steem:
* test for test_post improved
* test_sp_to_sbd and test_rshares_to_vote_pct added
tst_testnet:
* test_wallet_keys added  for testing the wallet
* test_transfer_1of1, test_transfer_2of2_simple, test_transfer_2of2_wallet and test_transfer_2of2_serialized_deserialized added thanks to @leprechaun

account
* function for reputation to score calculation
* Doku improved
amount
* better handling of offline mode
steem
* Doku improved
transactionbuilder
* handing of appbase for tx verify and broadcast improved
utils
* node list added as function
* not needed function removed
steemnoderpc
* handling of server errors improved
objects
* Amount fixed for appbase
exception
* RPCErrorDoRetry added, when a rpc call should be retried
grapherpc
* Handling of server error 500 to 511 added
* better handling when get_config does not work
unit tests
* nodes and nodes_appbase are take from utils
* keys is used instead of wif for Steem()
* unit test for broadcast added
* unit test for appbase for verify added
* test_operations added
* test_types added