Resolve #741: Add opening and closing price to market history
Merge branch 'develop' of github.com:BitShares/bitshares_toolkit into develop
No more duplicate keys used for wallet transaction scanning
Attempt to clean up peer connections better at shutdown and fix crashes at shutdown by preventing new async tasks from starting after the node starts destructing, and forcibly canceling the read_loop at the beginning of shutdown
Return wallet transaction records for all wallet transactions
adding restrictions on when covering is enforced
Don't cancel an ongoing scan when a new block comes in
Merge branch 'develop' of github.com:BitShares/bitshares_toolkit into develop
Merge remote-tracking branch 'toolkit/develop'

Conflicts:
	programs/qt_wallet
	programs/web_wallet
Fix build after merge