.emacs: remove c-style for ~/svn

I don't hack on Subversion anymore.
.emacs: simplify define-new-c-style

Take a simple path, not a path list.
.emacs: introduce define-new-sh-style; define 2 styles

~/src/zsh uses a different sh-indentation/sh-basic-offset from
~/src/git/t (chosen as the canonical ~ style).