Add support for Minecraft Pocket Edition worlds

[zhuowei]

Feature request (and potential pipedream):

It would be helpful to allow the renderer to read worlds created by Minecraft Pocket Edition.

PE worlds contain one RegionFile in little-endian (!) format, and chunks are not Gzipped or wrapped in NBT.

See the code in PocketInvEditor: https://github.com/zhuowei/PocketInvEditor/blob/master/src/net/zhuoweizhang/pocketinveditor/io/region/RegionFile.java for an implementation example. I guess a modification of World and Region should take care of it.

For more info: http://www.minecraftwiki.net/wiki/Pocket_Edition_Level_Format