[changed] iff files in the filesystem will override iff files from the
tres (similar to the client)
[added] support for FilterBitmap and targa height maps on non-backed
terrains

Change-Id: If85e74fe96e4604562152d1fa2f6a8b7b9078ecd
Merge "[changed] iff files in the filesystem will override iff files from the tres (similar to the client) [added] support for FilterBitmap and targa height maps on non-backed terrains" into unstable