two fixes in 0.9-alpha11

[Austin Hicks]

Hi,

Yet another alpha. Two bugfixes, both kind of crucial:


Firstly, loading from files no longer blocks the audio threads
significantly. This comes at the cost of a higher memory requirement
while it loads, but means that you won't get stuttering because you made
a new buffer. Essentially, a lock was being held during the decoding
and resampling process but is now held only for a few pointer
assignments. Some people were getting inexplicable slowness that
couldn't be tracked down; this may be why.


Secondly, there was a somewhat rare crash with
Lav_environmentNodePlayAsync to do with having 31 or more sounds playing
through that mechanism at once. It's hard to explain what went wrong
here, but basically an object representing a firing callback could end
up being deleted while the callback was still firing. This is related
to issue #21. We have a hacky workaround for now, but it'll fix itself
when I rearchitect callbacks to be harder to get wrong internally.