Fixed pixel alignment

I found a bug in my code; non-compressed-odd-width-24-bit textures failed to load. I uploaded texture lines aligned to 4-byte boundaries, but they shouldn't be in aligned Unity (my code is based on a OpenGL-specific DDS loader where lines have to be aligned by default). Even worse, I even read them as if they were 4-byte-aligned, because of my poor C++-to-C# conversion, which resulted in a crash.