Refine C indent settings

modified:   .gvimrc
	Source .exrc from $HOME.
modified:   .vimrc
	Put them all under autocmd.
	Set shiftwidth specific to the C modes.
	Keep a default sw=8 outside the C modes.
	Do not set smarttab or expandtab globally.
Clean up .gitconfig, add aliases

Matching the linux-home settings.

modified:   .gitconfig