IMAGES: Add PixelFormat
IMAGES: Add S3TC decompressor from xoreos
IMAGES: Add a Decoder class, mostly from xoreos
IMAGES: Add a TGA dumper from xoreos
IMAGES: Add Decoder::dumpTGA()
IMAGES: Add WinIconImage decoder from xoreos
IMAGES: Add image utility functions from xoreos
IMAGES: Add TGA decoder from xoreos
IMAGES: Add DDS decoder from xoreos
IMAGES: Add TPC decoder from xoreos
IMAGES: Add TBX decoder from xoreos
IMAGES: Add SBM decoder from xoreos
GUI: Add ResourceTreeItem::getAudioStream()
GUI: Use ResourceTreeItem::getAudioStream() in PanelResourceInfo
GUI: Use ResourceTreeItem::getAudioStream() in PanelPreviewSound
GUI: Add ResourceTreeItem::getImage()
GUI: Restructure PanelResourceInfo::update() a bit
GUI: Add Export as TGA button for images