Untangles dependencies by splitting up `engine.{h,cpp}` into 3 files:
1. `primitive_render`
2. `ticks` -- only contains `GetAnimationFrame` for now.
3. `GetWidth2` renamed to `CalculateSpriteTileCenterX` and moved to `levels/dun_tile.hpp`.
The format is almost identical to CL2, except it uses the frame header
to store frame width and height instead of 5 32-line offsets.
This means we always have access to frame dimensions, so we can use it
as an on-disk format for our graphics as well.
Additionally, we may be able to optimize the rendering even more
in the future now that we have guaranteed knowledge of frame dimensions.
Makes `CelSprite` unowned and adds a new `OwnedCelSprite` class for
owned sprites.
This clarifies ownership and makes the code cleaner in a number of
places.
Additionally, because the `CelSprite` class is now tiny (1 less
pointer), we can pass it by-value instead of by-reference, removing a
pointer indirection in the rendering functions.
Missiles _mimfnum is being used for a lot more then just directions and
can also be a 16 degree direction so can't apply enum verbs and
restricitons to it in most cases. This in turns also affects SetMissDir
and some other functions that have to stay int.
- Add file documentation to about 1/4 of the files in Source
- Copy over a lot of the documentation from the sanctuary/notes repo
- Standardise all the existing documentation
- Create a configuration for Doxygen
- Add more documentation (engine.cpp is now fully documented)