Rename function 'apply_keyhacmacs' -> 'call_if_enabled'
Modify define_keys as a dictionary of a list of functions
Change parameter name 'exe_names' -> 'target_exe_names'
Add set_mark, unset_mark. Change comments to lower cases.
Move unset_mark function into keymap lists of functions
Change property name 'is_mark' -> 'is_marked'