Minor changes to vimrc
Added Tabular.vim and NrrwRegn.vim
Changes to vimrc

I picked few of these changes from @yeban. Now selecting any text
in visual mode retains the selection even after indenting in or out.
Also increased the timeoutlen value.

Closes #1.

Signed-off-by: Vivek Rai <vivekraiiitkgp@gmail.com>