[Openal] Create multiply contexts

[Garin Hiebert]

> Are there any known iusses with two contexts? Or iam doing someting wrong?
>   

There are known issues, although they haven't been fully explored yet.  
I just recently added specific mutli-device/multi-context testing to 
Creative's test procedures, and there are bugs logged against it.  
Initial looks into the problem indicate that the router is having issues 
(what our installer installs as "openal32.dll").  Also note that in many 
cases (all the wrapper devices -- "Generic Hardware" and "Generic 
Software"), the library will only create one context per device -- 
that's not incorrect behavior by itself.

We do intend to fix the multi-device/multi-context issues, but that 
doesn't necessarily mean you're going to be able to get multiple 
contexts per device any time soon -- the fix may be to simply disallow 
this case where it is causing problems.

The only scenario where I'm fairly confident you can now run multiple 
contexts on a single system at once under Windows is one where you do 
the following:

1)  Install two sound cards, at least one of them being a Creative or 
NVIDIA card with native OpenAL support
2)  Enumerate available devices, selecting at least one native device as 
well as one of the "Generic" devices
3)  Open each device separately, opening one context on each

If the above somehow doesn't work now, that's the kind of bug that I 
intend to have fixed on the next release of the router.

Garin