working on global enum and image info

Added global enum support. That exposed one
big hole in bookmaker: The topic overview
should not be in the class or struct if
the topic includes multiple objects, which
is the case for SkImageInfo and enums like
SkColorType.

This straightens that out, and then used that
knowledge to strengthen the topics in
SkRect as a test. Now SkRect has more
groups of methods, and can expose and link
to sets of methods with the same name.

This work also is getting ready for tightening
SeeAlso data, to be checked as part of the
bots' tasks soon.

Also, remove links from markup for lowercase
method names unless the reference has
trailing parentheses.

TBR=caryclark@google.com
Docs-Preview: https://skia.org/?cl=98782
Bug: skia:6898
Change-Id: I35419c9789da17e272047bf7b9c95b1cf44bb7fe
Reviewed-on: https://skia-review.googlesource.com/98782
Commit-Queue: Cary Clark <caryclark@google.com>
Reviewed-by: Cary Clark <caryclark@skia.org>
Reviewed-by: Cary Clark <caryclark@google.com>
32 files changed