Added prefix and prefix_uses to etmtk.cfg to set the whitespace prefix for @keys in prefix_uses when displaying and saving items.  Cleaned up logging debug statements. Initialize options['user_data'] to avoid missing key errors.
Merge branch 'master' of https://github.com/dagraham/etm-tk
Fixed version info.
Added @z to prefix uses and moved it's position to the end of item_list.