Add config file variable for controlling libsamplerate conversion scale
factor. This is an alternative to the approach taken in the version on
the trunk version, where all sounds are pre-converted at startup and
adjusted based on the maximum value.

Subversion-branch: /branches/v2-branch
Subversion-revision: 2690
Preserve libsamplerate_scale in the setup tool.

Subversion-branch: /branches/v2-branch
Subversion-revision: 2691