Implement max staff number, other improvements

-) Calculate good max nr of staves per page
-) Staff size given in mm rather than pt
-) add 2-staff choir, tab staff, drum staff, etc.
-) typos
-) Add empty header fields for title etc.
-) good-looking footer line with links to Edition Kainhofer & LilyPond
-) no page numbers
-) Create 3 pages (1 title, 2 normal), page number not selectable by more
-) Add proper absolute pathes to the images and scripts, so the php code
   can be included in any page and will still access the correct files
	 in the source dir
-) Create .ly file only if needed, create smarty object only when needed
-) Disable access to the templates and other code via .htaccess