relax SVN archive

Improved the print outs of the scons 'binary_dist' target for Mac OS X.

Modified the 'clean' scons target to remove the py2app build and dist directories.

Created the 'scons binary_dist' target for Mac OS X.

Typing 'scons binary_dist' on a Mac will now create a DMG image of a universal Mac OS X application.

Added the Mac OS X DMG distribution file names to the scons script.

Modified the setup.py file so that the Mac OS X .app creation code is in the mac_setup() function.

This will be used by the scons system later on.

Updated the hdiutil command options for the Mac OS X DMG file creation.

Added instructions to the setup.py file for creating a Mac OS X DMG distribution file.

Removed the GUI wait_for_interpreter() method as this is replaced by the intepreter flush() method.

Mac OS X fix for the relaxation data list element - the height algorithm is now more robust.

The ListCtrl.GetSize() method appears not to work on Mac OS X!?! Therefore a different algorithm
has been designed to get around this Mac specific problem.

Fix for the relax_fit.relax_time GUI user function.

The combobox GetValue() call has been replaced by GetStringSelection() for the spectrum ID.