Merge pull request #16 from vikramrajkumar/btsx

merge + mainnet changes
hard fork number and add checkpoint
update submodule
Fix build
merge from upstream/develop
Fix regression tests
Fix submodules
Remove misleading wallet rescan progress bar
Don't automatically relock wallet when there are enabled delegates
Set scan progress to -1 when attempting scan while scanning disabled
Fix the Heisenbug!

push_block calls now(), which yields on its first invocation, but
push_block is a non-premptable function. To resolve this, we add a call
to now() at the beginning of chain_database::open, to ensure that now()
has already been called by the time push_block runs.
Add block limit to blockchain_market_order_history

It is unfun to sit there while the history function hunts through 200000
blocks of chain, trying to find orders. Let's not do that unless we
really, really want to.
Merge branch 'develop' of github.com:BitShares/bitshares_toolkit into develop
add filtering market orders by account name
merge from upstream develop
test for issue_633
clear executed market transactions when we run out of depth
increase max block size and broadast rate
Fix crash: chain observer notifications should be asynchronous

Chain observers are free to yield if they wish, but nothing in the
push_block call stack should ever yield, so chain observer notifications
ought to be made asynchronously. This commit makes it so.
Fix wallet_backup_create