Update projects.
 * SDL updated to 2.0.3 (5b6a0bbd6d1713461187afe715b0fca452febeb7)
 * SDL no longer linked in statically to comply with SDL2's new dynamic API.
 * Replaced SDL_RWFromFP() use as it's not supported in Windows.
 * SDL_Image updated to 3d06660c46d153af0f0e06e3136b9c22e013ddaa.
 * libpng updated to 1.6.10.
 * Removed unnecessary build configurations.