another attempt to fix #218: get deterministic, sequential behavior when substituting the "nwjs" string for "Purr Data" in the OSX app bundle

Fix up misleading tooltips for the Ok/Apply/Close buttons of the Preferences dialog. These apply to the prefs dialog as a whole, not just to the audio properties.

first shot at fixing issue #218: error when trying to install on OSX. See if using a temporary text file will work around the bug of plutil creating empty files

port moonlib/mknob, and fix an iemgui dialog bug with empty strings not getting changed to zeroes for numeric fields