install: pathogen; also move vimrc inside .vim
install: SrcExpl.vim bundle as a submodule
_minor_: fix indentation of vimrc
install: taglist bundle as a submodule
_minor_: fix commented out part for Trinity
install: Trinity bundle as a submodule in Trinity/plugin folder

Trinity repo itself is a flat folder with *.vim's inside;
pathogen seems failing to load it as the *.vim's are not
organised in a plugin folder.

Thus it is put under `bundle/Trinity/plugin` rather than
`bundle/Triniy`.
_refine_: assign F8 to Trinity
install: fugitive bundle as a submodule under fugitive folder
install: cscope_maps bundle as a submodule under cscope_maps folder

Usages:
 * s symbol:  find all references to the token under cursor
 * g global:  find global definition(s) of the token under cursor
 * c calls:   find all calls to the function name under cursor
 * t text:    find all instances of the text under cursor
 * e egrep:   egrep search for the word under cursor
 * f file:    open the filename under cursor
 * i includes:find files that include the filename under cursor
 * d called:  find functions that function under cursor calls

([Ref](http://cscope.sourceforge.net/cscope_vim_tutorial.html ))
setting: autoload cscope.out from upper folders