New PNG encoder that supports compression, more efficient vertical flipping, and minimal allocation when encoding multiple PNGs.

closes #2501
Fixed PNG encoder for all pixmap formats.

#2501
Fixes #2512
Better way of specifying initial buffer size.
Merge remote-tracking branch 'origin/master'
Added renderObjects() to TiledMapRenderer
Merge pull request #2514 from Arcnor/master

Added renderObjects() to TiledMapRenderer