[sdlsound] modplug

[Ryan C. Gordon]

> 1. How do I use sdl-sound to playback modules with modplug?

Don't build in mikmod support and modplug will pick up these modules. I 
think there was a reason we favor mikmod, but I can't remember why now. 
There isn't a way to favor one decoder over the other, other than to not 
compile in support for the decoder that has higher precedence.

Is it mikmod that is broken on your modules, or how we use it?

> 2. If possible how do I pass settings to modplug?

You can't, without modifying SDL_sound and breaking the API's abstraction.

--ryan.