1. Moves more assets-related stuff from `init` to `engine/assets`.
2. Removes `SDL_audiolib` dependency from `soundsample.h`.
3. Cleans up some unused/missing includes.
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`.
For monsters with the same sprite, load the sprite from the file system only once.
Example:
```
VERBOSE: Loaded monster graphics: falspear\phall 452 KiB x1
VERBOSE: Loaded monster graphics: skelbow\sklbw 618 KiB x1
VERBOSE: Loaded monster graphics: skelsd\sklsr 610 KiB x1
VERBOSE: Loaded monster graphics: goatbow\goatb 832 KiB x1
VERBOSE: Loaded monster graphics: bat\bat 282 KiB x2 <-- here we only load the sprite once
VERBOSE: Loaded monster graphics: rhino\rhino 1306 KiB x1
VERBOSE: Loaded monster graphics: golem\golem 298 KiB x1
VERBOSE: Total monster graphics: 4401 KiB 4684 KiB
```
Here, the bat sprite will be loaded from the MPQ only once.
For the second sprite, we simply clone the first sprite before applying TRNs.
This also reduces the size of `MonsterData` from 88 bytes to 80.
When we migrate monster data to a TSV, the sprite IDs can be generated automatically at load time.
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.
Eric Robinson
Andrettin
Anders Jenbo
staphen
obligaron
Gleb Mazovetskiy
KPhoenix
Mikołaj Piróg
Cesar Canassa
ephphatha