Soften tabs in vimrc; add multiline stmts.

Mod:
	zshrc, tmux.conf
		-break lengthy statements (>79 characters) across multiple lines with
		escaped line breaks.

	zshrc
		-change git command aliases to use "git" instead of "g", my alias for
		"git", for portability should I ever change "g" to something else.

	vimrc
		-convert keyword keymaps (eg `imap #h #header `) to abbreviations,
		and add cpp as a target filetype in addition to just c, for header
		files.