get_account_history may terminate early due to using first op as sentinel value

[theoreticalbts]

Calling get_account_history on the account which owns get_object 1.11.0 may cause the iteration to stop early because of a confusion between two cases:

• Case 1: There is no next operation_history_object, we have reached the end of the list
• Case 2: The next operation_history_object exists and has ID zero

The simple fix for new chains is to create a dummy sentinel operation_history_object with ID zero. However, this fix will not work on already-deployed chains because it will change history ID's.

A deployable fix would append 1.11.0 to its result when:

• The account for which the operation history is being requested is the account for 1.11.0
• Appending it would not exceed the request limits

[vikramrajkumar]

This issue was moved to bitshares/bitshares-core#168