identify TODO tests by "TODO" in name

Allow tests to be marked as TODO and skipped if TODO appears in their
name.

Ideally these tests would still run and be marked as TODO, but this
doesn't seem possible under Test::Base.
add failing TODO tests for HTML entities

At this time, Template::Semantic doesn't correctly handle HTML
entities:

https://github.com/tomi-ru/Template-Semantic/issues/4