statecheck: added support for STATES This removes `STATES` from `state.py` and adds support to `statecheck` class to handle its features. `getrepostate()` function is modified accordingly. This adds a method 'cmdutil.addunfinished()' for appending to the unfinishedstate list so as to keep 'merge' and 'bisect' at the last. This also makes two separate message formats for `checkunfinished()` and `getrepostate()` as there were previously present. Results of test changed are shown. Differential Revision: https://phab.mercurial-scm.org/D6503