Test application crashes when playing with multiple sources and convolutional reverb

[areyesl]

Actions to crash:

• Open a second source
• Play both
• Disable convolutional reverb
• Stop one of the sources
• Enable convolutional reverb again ---> crash

It seems that when reverb is disabled, ir remembers that two sources were being included in the reverb. Then, when it is enabled again, only one is active and that seems to create a conflct.

More specifically, the problem occurs when two sources are loaded and one of them is stopped. The loop in CEnvironment::ProcessVirtualAmbisonicReverbThreedimensional() iterates through all sources, not only those being played.

In Environment.cpp, line 1032, it is checked if every source has updated the buffer. When a source is stopped, it doesn't update the buffer, but this control prevents the crash. However, when the reverb is switched on, in the first frame, this control fails and the app crashes