vimrc: raise color count from 8(!) to 256
install.sh: improve the installation script

relax the "regular file" check, to also symlink dirs like ~/.vim
but still, existing dirs (e.g. .subversion, .config) are kept as is
install.sh: a tiny bit of alignment
vimrc: disable the python "compiler" for now
vimrc: make background flip
vim: install the vim-pathogen as a submodule
vim: add a few colorschemes as submodules