Hopefully fixed the chaos with the SAGA volume values. This also fixes the broken volume introduced with the introduction of the RTL code in the engine

Files:
modified: /scummvm/trunk/engines/saga/rscfile.cpp (try)
modified: /scummvm/trunk/engines/saga/interface.cpp (try)
modified: /scummvm/trunk/engines/saga/music.cpp (try)
modified: /scummvm/trunk/engines/saga/sfuncs.cpp (try)