Using references matches the C++ coding style better and should improve
performance a bit in theory. It avoids 2 copies of T in case of the
functions registered with RegisterFunction (mainy used in the GUI). It
should also avoid one or two copies in case of
DEFINE_INTERFACE_METHOD_X, which is used in the simulation, but I
haven't bothered to count it there exactly.
It is now predefined which types have to be passed by const reference
and which are passed by value. Note that references can't be used as
out-parameters (to return multiple values to JS). This hasn't worked
before either and probably never will.
This was SVN commit r17696.
Support sound group playback from simulation scripts. See #486.
Update some sound group files to sound better for rough testing.
Clean up CSoundGroup a tiny bit.
This was SVN commit r7437.
