Many changes.

* Removed <C-O>s mapping for 'GoldenView', for it conflicts with vim's built-in <C-O>.
* ', ", (, [, {, in visual mode will do the corresponding 'surround' job.
* Use <C-9>, <C-0> to repalce <C-P>, <C-N> for 'YankRing' respectively, because
  they confict with 'multi-cursor'.
* Use <C-,>, <C-.> to repalce <C-E>, <C-D> for 'Ultisnips' respectively, because
  they confict with vim's built-in mapping <C-D> in insert mode.
* New plugins:
    Gundo
    vim-autoformatter