Update vital-over
Improve command line for find motion

Add:
  - autocmd User
  - InsertRegister
  - EMCommandLine Map, NoreMap, UnMap
  - Emacs like keymapping by default

Change:
  - Modify default buffer completion key from <C-d> to <C-l>
Update doc: command line for find motion
Update vital-over
Remove on_cancel & use exit_code()
Update doc: minor change
Merge branch 'improve/commandline' into dev