NodeList
* replaces get_node_list from utils.py
* is a list and contains all nodes as dict
* get_nodes() returns the url in a list
Utils
* get_node_list removed
Unit Tests and Examples adapted to the 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

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

Transactionbuild
* add clearWifs
Examples
* use nodes from get_node_list
test_testnet
* improved tests for Transactionbuilder

blockchain
* reduced times in which get_current_block_num is called
* when last_fetched_block_num is given, get_current_block_num is only called when block_number is greater than last_fetched_block_num
storage
* default nodes list enhanced
steemnoderpc
* Service Temporarily Unavailable and Bad Gateway added to exception detection
graphenerpc
* check for Service Temporarily Unavailable and Bad Gateway
* Improved handling of Client returned invalid format. Expected JSON! when output is int
Unit test
test_utils fixed

steem
* Robustify reading of blockchain parameters
utils
* improve formatTimedelta output
Examples
* improve benchmark_nodes by added account history

* Fix blocks for threaded and batched calls
* add blockchain_version function on steem
* Fix node input on graphenerpc
* Improve benchmark_nodes
* Add unit tests for bateched and threaded blocks calls
* Use https://api.steemit.com as default appbase node

test_testnet improved

Transactionbuild
* Automatic Signing with owner key removed
Beembase/account and beembase/bip38 removed as they are using beemgraphenebase/bip38 and beemgraphenebase/account