[VIM] Fix: Ctrl+N to switch between absolute and relative line number.

Signed-off-by: Wei-Chung Wen <morisato3711@gmail.com>
[VIM] Relative line number as default.

Signed-off-by: Wei-Chung Wen <morisato3711@gmail.com>
[VIM] Minor refactory.

Signed-off-by: Wei-Chung Wen <morisato3711@gmail.com>
[VIM] Add new snippet for check framework and refactor old one.

Signed-off-by: Wei-Chung Wen <morisato3711@gmail.com>