Make the text image readable under recovery

Encode the width, height and locale of the localized image as pixels so
that recovery can locate the correct range of the image from a
concatenated png file.

Also address a few todoes including wrapping the CJK text, making a
catch-all type for all languages.

Test: view the generated image under locale test
Change-Id: Icd3997eb4e992e76ef72526787d64c406f606970