Use the Ctrl+O command escape in insert mode when mapping F2 to :w

This allows us to save the file from insert mode.
Use the nohl command to remove las search highlight.

Also changed the F12 shortcut so it does not clear last search but only removes
highlight.
Use :update instead of :write for F2.
Map ,s to sort selected lines in visual mode.
Added indent (>)/unindent (<) friendlier in visual mode.