addedAll event incorrectly emitted for *each* texture when loading 2nd pack

[deathcap]

Test with game-shell-voxel, press P to invoke voxel-artpacks UI, drag another pack (MC175.zip) into the list -> the pack reloads very slowly, because voxel-stitch is emitting the addedAll event for each and every texture loaded.

It is supposed to only emit when all of the pending textures have loaded, so gl-tile-map can calculate all the mipmaps quickly all at once (instead of recalculating continuously). To do this it maintains this.countLoading and this.countLoaded, loading set to textureNames.length in stitch(), and loaded incremented in each addTexturePixels() (async callback from addTextureName, from artpacks getTextureNdarray). If loaded >= loading, then addedAll is emitted; loading isn't being reset for some reason so this condition is always true for all the textures loaded in the second pack.

[deathcap]

Use https://github.com/caolan/async#each? Calls back when all of the function calls (for each iterated element) complete. Instead of:

for (var j = 0; j < textureNames.length; j += 1) {
var textureName = textureNames[j];

this.addTextureName(textureName, this.nextY, this.nextX);
this.incrementSlot();

}

Something like: async.each(textureNames, function(name, done) { // include Y, X in item
self.addTextureName(name); // pass and call done()

[deathcap]

Changed to use async module on 'async' branch but curiously, loading a second pack fails with "Callback was already called.", at:

this.artpacks.getTextureNdarray(textureName, function(pixels) {
  console.log('addTextureName callback',textureName,'calling addTexturePixels',tileY,tileX);
  self.addTexturePixels(pixels, tileY, tileX);
  callback(); // here

something broken with getTextureNdarray()?