Scheduled weekly dependency update for week 29

rework Conveyor signing, revert ecdsasig changes

This reverts commit c08c815d.

Initial Conveyor integration

* save_draft()
* list_drafts()
* remove_draft()

Methods:
* `get_user_data()`
* `get_feature_flags()`

* Switch to condeser call for list_witnesses with by_vote_name
* changed steemconnect url
* add check in transactionbuilder

Comment
* dpeth property added

Adding account methods for feed, blog, comments and replies

fix spelling errors reported by misspell

Snapshot
* update_in_vote added 
* enable_votes changed to enable_in_votes and enable_out_votes
* build_rep_arrays added
Example
* account_vp_over_time added
* account_reputation_by_SP added
Discussion
* check if parameter exists in discussion_query added

Scheduled weekly dependency update for week 28

discussions: allow empty replies

setting `set_next_node_on_empty_reply` for Discussions_by_feed and
Discussions_by_comments
Fixes #54

fix discussions.Replies_by_last_update()

`start_parent_author` parameter was missing in the RPC call and the
Query class.
Fixes #52

discussions: set steem inst. as keyword argument