Changed test images and Texture2D class to use TGA format.
Merging new Image2D work from Linux build.  Resolving conflict in Megacorp.cpp.
Implemented Image2D class with support for loading and writing greyscale, uncompressed color, and RLE compressed color TGA images.  Changed member variable format for Color, TileHex, and TileMapHex classes.
Removed Texture2D class. Functionality replaced by Image2D.
Switched classes that were using Texture2D to use Image2D. Added 24 bit exporting for TGA files.
Removed DevIL dependancy from CMake.  Added support for reading and exporting RLE greyscale TGA files.
Refactored writing packets for TGA exporter into separate functions.
Cleaned up RLE TGA image exporting.