Minor refactor to assign texture slots first, then populate (to ease async transition GH-2)
Whitespace
Emit loadedAll on multiple of texture count, not >=. Closes GH-2

The texture load callback can be called multiple times -- it is called
by the artpacks module when the texture is reloaded (when a new pack is
added), even without explicitly calling stitch().
Cleanup logging
0.2.1