[Texturepacker] - removesdl

This removes SDL from TexturePacker and replaces its functionality in favor of an imagedecoder abstraction with with implementations for libgif, libpng and libjpeg. This is a followup of the last devcon discussion for the goal to remove SDL (which might be a bit liquid now).

@davilla here it is ...

It also fixes the completly broken win32 projects files and removes MakeDDS because it wasn't used @MartijnKaijser  @ronie - correct me if MakeDDS was used by some then i will try to fix it - but its a pita.
Agreed but the annoying thing is that its .so on linux and .dylib on osx. Need to find an example where we somehow checked the correct one on the corresponding platform.