Enabled prog-mode-hook, update cmd/x, new cmd/mk-systags

modified:   .emacs-shared
	auto-fill was failing on sh-mode (disabled by mistake because it
	looked like shell-mode). now prog-mode-hook enables what i normally
	use in all programming modes: auto-fill, font-lock, and hide-show. the
	extent of the support is, of course, dependent on the major modes.
modified:   cmd/x
	fixed a bug in the way sakura was being launched.

new file:   cmd/mk-systags
	tries to create a tags files for the gcc default header
	directories. it is not ready (/usr/include adds too much to the tags
	file).