When using `UNPACKED_MPQS`, avoid all the SDL machinery for reading
files.
This is beneficial not only due to reduced indirection but also because
we can test for the file's existence and get the file size without
opening it, which is much faster.
* Non-int versions of `Point` and `Displacement`
This will allow us to make some structs, such as `ActorPosition`, much
smaller.
* ActorPosition: Use smaller types
`Monsters`: 56K -> 46K
* player.cpp: Reduce size of `DirectionSettings`
* CrawlTable: Displacement -> DisplacementOf<int8_t>
* CrawlTable: vector<vector> -> array<vector>
Also only allocate one vector during construction instead of two.
A bit less indirection.
* Monster#enemyPosition: Point -> WorldTilePosition
sizeof(Monster): 240 -> 232
* Monster: Further optimize field layout and sizes
sizeof(Monster): 232 -> 208
`Monsters` is down to 40,000 bytes
* DMonsterStr: _mx/_my -> position
Previously, the memory for each frame was allocated separately.
Changes it to allocate a single buffer for all the frames.
This has the following advantages:
1. Less bookkeeping overhead in the allocator.
2. Less alignment overhead (allocator results are max-aligned by default).
We can follow this up with a similar treatment for other multi-file
animations.
Gleb Mazovetskiy