oleaut32: Clean up IFontDisp::Invoke by using VariantChangeTypeEx to coerce the input parameter into the correct type.

Instead of blindly dirtifying the surface LoadTexture keeps track of
the color key that was used when creating the opengl texture and
reloads the surface if the color key has changed.

ntdll: Renamed the NTDLL_get/from_server_timeout functions since they don't deal only with timeouts.

Also get rid of the unused timeout field.