Add -html, and mark it as IGNORED for now due to qdoc segfault.
Python and (unless I'm mistaken) are needed for tests, so add them
to TEST_DEPENDS, too.
Zap variable unused anymore.
Improve dependencies a bit.
Start packaging Qt5.

Still no HTML documentation, sorry.
Package descriptions for Qt5.
More packaging tweaks.

TODO is updated as well.
Move TODO to a separate file.