[Vim] Enhance <F10> mapping.

Change-Id: Ia223f3b318e2ecf6c522e7f0d6113c02dabef40b
Signed-off-by: Wei-Chung Wen <morisato3711@gmail.com>
[Vim] Map F12 to TagList and NERD toggle.

Change-Id: Iaa388a79e92f1c0ab7b371f2c86bb80708d079bd
Signed-off-by: Wei-Chung Wen <morisato3711@gmail.com>