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
$ rm -rf a
$ hg init a
$ cd a
$ echo a > a
$ hg ci -Am0
adding a
$ hg tag t1 # 1
$ hg tag --remove t1 # 2
$ hg co 1
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg tag -f -r0 t1
$ hg tags
tip 3:a49829c4fc11
t1 0:f7b1eb17ad24
$ cd ..