[aquaria] SDL2 patches...

[Ryan C. Gordon]

> 3. For the Steam version, if the Steamworks components can be spliced
> into a separate library, it could allow the actual game code to come
> under open source territory.

We can't link GPL code against the Steamworks SDK, period. It's not a 
technical concern, it's a legal one.

> recompile without having to touch the Steamworks portion. Right now
> Steamworks is used pretty much just for achievements, so having a
> "dummy" local library for the open source version and another
> Steamworks library for Steam would, in my opinion, work just fine.

More or less, that's how it works now. If you don't have Steam, we still 
"unlock" achievements and take note of it in your savegame directory.

--ryan.