this to show a "your thumbs/resizes are out of date" message whenever
we change the graphics rules. Tweak watermark module to add graphics
rules whenever we make a change, which triggers the graphics module to
add the permanent message.
Change admin/watermarks/upload -> admin/watermarks/add for consistency.
Internationalize position text, store it as text in the database,
display it to the admin.
Make i18n strings consistent to reduce l10n load.
