[vimrc] smooth motion between windows

Mapping to move through windows with <C-[hjkl]>
<C-n> now replaces vim latex <C-j>
[bashrc] prompt more dynamic and out of bashrc

The prompt is now in a dedicated file, __git_ps1 settings are now interactive
(which is usefull for huge git repo)
[tmux.conf] new configuration more vim friendly