necessary.

When called without optional 'subDir' argument, the path to the
root configuration folder is returned (and the folder optionally
created if it doesn't exist yet). When 'subDir' is given, the
path to the subfolder 'subDir' inside the root configuration
folder is returned - and the 'subDir' created inside that folder
if neccessary. Subfolders are useful to group related
configuration data, e.g., all settings for DAQ toolbox, all
display calibration settings, etc.

3/7/08 mpr streamlined this
3/8/08 mk A bit more of streamlining - Don't write the
PsychPrefsfolder.m file anymore.
4/28/08 mk Made compatible with Octave, added 'subDir'
option.
6/14/09 mk Remove Octave code -> Not needed anymore.