moved first-letter-generater script + template to work-in-progress/mozilla

--HG--
rename : css21/first-letter-characters-generator.py => work-in-progress/mozilla/first-letter-characters/first-letter-characters-generator.py
rename : css21/first-letter-characters.tmpl => work-in-progress/mozilla/first-letter-characters/first-letter-characters.tmpl