Fix bug in get_next_ask

Covers were being considered prior to their expiration date due to an
inverted inequality.
Fix for shorting with non-XTS base
Major refactor of market engine

Fix several bugs and general code cleanup
updated js api generator to place error handler to end of parameters list, default value is null
Update/refine market engine
Fix for skipping proper order
Merge branch 'dryrun-19' into develop

Conflicts:
	libraries/blockchain/market_engine.cpp
	programs/web_wallet
Fix merge
Update submodules
Use time_point_sec instead of time_point to match everything else
Remove no longer used market depth references
Reduce frequency of "..X active connections..." messages
#778
Report the current head block id/number/time in initial connection message
Add the remote node's current head block (guess) to the info displayed in 'network_get_peer_info' cli command
Remove old check for null _p2p_node that hasn't been necessary for months.
Merge branch 'develop' into btsx

Conflicts:
	programs/qt_wallet
	programs/web_wallet
Fix compile error (excessive qualifiers)
Merge branch 'develop' into btsx
Update submodules
Merge pull request #74 from vikramrajkumar/btsx

Merge upstream