Allows Content objects to control how magic worlds are applied to it.
Useful mainly when magic words are used outside the parser.
Change-Id: I9711f580f8beadfb9f93a706f87c97c7cf667f6c
On Tim's request, this change moved getParserOutput() and getSecondaryDataUpdates()
from the ContentHandler to the Content interface.
Change-Id: Ia654aa8710a242ba5fe7a4eb528e6a6449035f59
Representing content_model and content_format as integers in the
database was suggested by Asher mainly to save space.
This change entails some refactoring and renaming, but no big
change in logic.
