Update cmap_block_coverage to limit scripts, trim output.
Update cmap_block_coverage to limit scripts, trim output.

Sometimes it's useful to see block coverage only for some scripts.
When you do that, you don't want to see information about all the uncovered
blocks/characters.  This lets you limit the scripts covered and omits the
unwanted information.

googlei18n/nototools,googlei18n/nototools,dougfelt/nototools,googlefonts/nototools,googlefonts/nototools,dougfelt/nototools,googlefonts/nototools,anthrotype/nototools,anthrotype/nototools,googlei18n/nototools,dougfelt/nototools,googlefonts/nototools,anthrotype/nototools,moyogo/nototools,moyogo/nototools,moyogo/nototools,googlefonts/nototools