cleanup: removing old stuff

	modified:   _layouts/category_index.html
	modified:   _layouts/default.html
	deleted:    images/bg_hr.png
	deleted:    images/blacktocat.png
	deleted:    images/icon_download.png
	deleted:    images/sprite_download.png
	deleted:    javascripts/main.js
	deleted:    params.json
	deleted:    stylesheets/pygment_trac.css
	deleted:    stylesheets/stylesheet.css