They no longer spin like crazy. I don't know how, but I must have broken
something over the years as I'm sure Seth had the code working (and I
seem to remember seeing it working). In the process, clean up a lot of
the angle mess.
It's a lot easier to read (and see the difference between modes 2 and 3)
with all the ifs removed, and the state is properly is chasestate_t now
(though not handled properly on level reset etc).
The more advanced modes are rather broken (continuous spinning), but
they may have been for a while. The bulk of the various changes were due
to renaming viewstate's origin and angles to make their meaning more
explicit.
Handling of view angles is a little hacky at the moment, but this gets
the chase camera code and most of the common input code into one place,
which will make cleaning up the camera code much easier.
