Support 'ok', 'warning', 'error' annotations and define some.

Formerly the annotations file created a set of sequences that would
cause the name field to display with a special background color.  This
lets you choose one of three colors by defining the 'type' of annotation
in the file.  The file format was enhanced and the code using it takes
the type of annotation into account.

This also adds a sample annotation file with annotations for a number of
situations we currently expect to encounter: missing images that we expect
to be supported by aliases to other images, flags that we expect to not
support, and new unicode 10 emoji that we might not yet have image data
for.