Alignment should be taken care by the surface pitch and
GL_UNPACK_ROW_LENGTH alone just fine, as long as the pitch is a
multiple of the pixel size. Client APIs respect that,
internally we need to do the same and the changes to
surface_load_texture and wined3d_volume_upload_data are there
for this reason (e.g. WINED3DFMT_R16G16_SNORM is emulated with
GL_RGB16 when NV_texture_shader isn't supported).

At this point it doesn't really add anything anymore.

The idea is to make it clear that wined3d_texture_load is responsible
for checking the color key for changes. Once we can do color keying in
the shader we also have one place where we can disable the surface
conversion.

This fixes a regression with color keyed mipmaps that was introduced by
ee8a5b7d. surface_load for level n+1
would call texture_force_reload, thus removing level n from the GL
texture.