Just some cleanup work

Subversion-branch: /trunk
Subversion-revision: 2849
* Tracking of current environment in high level sound engine
* Notification of environment change to reverb engine
* Notification of active reverberation to low level sound code
* Minor cleanup in z_native

Subversion-branch: /trunk
Subversion-revision: 2850
* Nine environmental reverb presets defined in base/sounds.edf
* p_testenvironment console command added

Subversion-branch: /trunk
Subversion-revision: 2851