tests/test-empty

merge: introduce tool.check parameter

tool.check is a list of check options, and can be used in place of
tool.checkchanged and tool.checkconflicts:

Equivalences:
tool.checkchanged = yes
tool.checkconflicts = no
tool.check = changed

tool.checkchanged = no
tool.checkconflicts = yes
tool.check = conflicts

tool.checkchanged = yes
tool.checkconflicts = yes
tool.check = changed, conflicts

Add _toollist() wrapper for ui.configlist() to implement this consistently.

checkchanged and checkconflicts are still supported, but check is
preferred for implementing new check options.

#!/bin/sh

hg init a
cd a
hg log
hg grep wah
hg manifest
hg verify
ls .hg
ls .hg/store

cd ..
hg clone a b
cd b
hg verify
ls .hg
ls .hg/store