Audaspace: fixing problems for the merge to master suggested by Campbell and Sergey.

- rename WITH_EXTERNAL_AUDASPACE to WITH_SYSTEM_AUDASPACE.
- rename C/PYAUDASPACE to AUDASPACE_C/PY
- simplifying cmake defines and includes.
- fixing include paths and enabling WITH_SYSTEM_AUDASPACE for windows.
- fixing scons building.
- other minor build system fixes.

source/creator/CMakeLists.txt

@@ -794,6 +794,16 @@ elseif(WIN32)
 			DESTINATION "."
 		)
 	endif()
+	
+	if(WITH_SYSTEM_AUDASPACE)
+		install(
+			FILES
+				${LIBDIR}/audaspace/lib/audaspace.dll
+				${LIBDIR}/audaspace/lib/audaspace-c.dll
+				${LIBDIR}/audaspace/lib/audaspace-py.dll
+			DESTINATION "."
+		)
+	endif()
 
 	if(NOT CMAKE_CL_64)
 		install(