remove $plural 's'. That's a language concept, belongs to language file.
And the code didn't work anyway.
File attachment was restricted to .php which wasn't the case in 1.6.
Alternative approach: if it's not a color, it's a file.
theme disporder is mandatory, thus should be updated by default
call update_theme_stylesheet_list() when saving disporders
allow 0 as a valid disporder
Merge pull request #1362 from frostschutz/feature-themes

theme/stylesheet quirks