Implement QSound support

src/engine/dispatch.h

@@ -97,6 +97,9 @@ enum DivDispatchCmds {
 
   DIV_CMD_SAA_ENVELOPE,
 
+  DIV_CMD_QSOUND_ECHO_FEEDBACK,
+  DIV_CMD_QSOUND_ECHO_LEVEL,
+
   DIV_ALWAYS_SET_VOLUME,
 
   DIV_CMD_MAX
@@ -217,6 +220,13 @@ class DivDispatch {
      */
     virtual int getRegisterPoolSize();
 
+    /**
+     * get the bit depth of the register pool of this dispatch.
+	 * If the result is 16, it should be casted to unsigned short
+     * @return the depth. Default value is 8
+     */
+    virtual int getRegisterPoolDepth();
+
     /**
      * get this dispatch's state. DO NOT IMPLEMENT YET.
      * @return a pointer to the dispatch's state. must be deallocated manually!