conftypes: Fix String length check.
conftypes: Fix none_ok for many types.
conftypes: More max >= min checkes.
conftypes: Use slicing instead of rstrip.

"100%%".rstrip('%') would give use "100" instead of "100%" which is not what we
want.
conftypes: Fix minint/maxint validation in PercList.
test_conftypes: Add more tests.
conftypes: Fix is_none in all types
conftypes: Various bugfixes/cleanups/tests.
conftypes: if -> elif
conftypes: Treat rgb(...) etc. as valid for QssColor
test_conftypes: Add more tests.
usertypes: Move QSS_FONT_REGEX to class.
test_conftypes: Add (broken) Font tests.
Accept prompt_accept in KeyMode.yesno
Update BUGS/TODO