Update Vundle configuration

- Use new Vundle syntax and update plugin list.
Add a self-evident comment
Improve CScope support

- Automatically load cscope.out if it can be found
Improve clipboard support for vim with -clipboard

- If vim is compiled without clipboard support, make use of xsel
Add Q mapping

- Add a mapping (Q) which allows recordings (from register q) to be played
  on visual ranges
- Improve comment consistency