The final line wasn't encoded correctly.
Also removes unnecessary `src` increments at the end of the encoding
functions.
```
Re-encoding dungeon CELs: 1,119 frames, 738,836 bytes
Re-encoded dungeon CELs: 1,119 frames, 721,604 bytes
```
Triangles in the dungeon CEL data have two redundant 0x00 pixels every other row.
Re-encodes the dungeon CEL data to remove these pixels in order to save RAM and simplify the rendering code.
Example RAM savings:
```
VERBOSE: Re-encoding dungeon CELs: 1,119 frames, 738,836 bytes
VERBOSE: Re-encoded dungeon CELs: 1,119 frames, 722,552 bytes
```
Performance remains the same. The rendering code is now a bit simpler.
Gleb Mazovetskiy