price feeds are now implemented
only keep a short undo history
adding market fees to asset record
Add new RPC call, wallet_account_update_active_key and regression test

Add a new call to update the active key and write a test to verify that
it completes successfully and can be imported into a new wallet. More
testing is necessary.
Fix is_unique_account wrt updated active key

Previously a wallet account was considered different from its blockchain
counterpart if the active key had been updated. This is no longer the
case.
Add regression tests mentioned earlier

Oops, forgot to check these in... :]
Merge branch 'develop' into update_active
Basically redo a8f6808928eb5aa63d6b07738b789489e1898794
Update regression test: update_active_key
price feeds and median price are now both used to restrict the market
bug fixes
Some fixes wrt importing active key for registered account
fix user issued markets
Implement wallet scanning for updated keys
fix bid/buy/keyid
Fix bug in how wallet_db stores account records and update tests

Previously, the account record was stored only by account address, but
not by active addresses. This caused problems when the active address
did not match the account address. This is now fixed.

Also, add tests to verify that sending a transaction to an account with
an updated active key is working properly.
Add regression test for update_active_key: transfer from updated account
Merge branch 'develop' into update_active
Merge branch 'develop' into update_active
Merge branch 'develop' into update_active