OpenALEffects

Ground work, this commit enables reverb zones and opens the slots for
other effects to be added later. Tested using the full template. Build
your openal dll and your full.exe use one of the environment presets and
it will work

Engine/source/sfx/sfxDevice.h

@@ -178,6 +178,9 @@ public:
       
       /// Set the rolloff scale factor for distance attenuation of 3D sounds.
       virtual void setRolloffFactor( F32 factor ) {}
+
+      /// send empty function to all sfxdevices
+      virtual void openSlots() {}
       
       /// Set the global reverb environment.
       virtual void setReverb( const SFXReverbProperties& reverb ) {}