Added some core files for the PyQSO program:
- pyqso.py: the main file. Sets up the GUI and starts the event loop.
- menu.py: defines the GUI's menu. The first step towards moving GUI setup-related code out of pyqso.py.
- adif.py: defines the ADIF class for the manipulation of ADI files.
- record.py: defines the Record class. Record objects contain various ADIF fields and associated data.
- logbook.py: defines the Logbook class. A Logbook object contains various Record objects.
- COPYING: contains the GNU General Public License (version 3).

This is the initial bzr revision of these files.
Added a data entry panel for adding/removing/editing records in the logbook. Each logbook cell itself no longer needs to be directly editable.
Remove the booleancell_edited_callback function, since cells are assumed to be only string-based.
Remove commented out code regarding .adx files, which are not yet supported.
Started to hook the data sources up with the logbook.
Move the new/open/save log methods to the Logbook class.
Update some comments.
Add methods to enable and disable the data entry panel. This will be useful to prevent user input when no record is selected.
Enable/disable the data entry panel as required.
Hooking the data sources up with the logbook.
Renaming set_field to set_data, and get_field_data to get_data, for consistency.
If a record in row n has just been deleted then the tree will automatically go to row n+1 after deletion, rather than staying at row n. Since row n+1 might not have a record associated with it, let's do some error handling.
Small comment update.
Added a new line at the end of the file.
Added a toolbar so the user can add, edit, and delete records.
Changed the layout so a new Dialog appears when a user wants to add or edit a record.
Remember to change the import statements now that data_entry_panel.py has been changed to record_dialog.py.
Improvements on the new "Update Record" dialog.
Add tooltips for the add, edit, and remove buttons.
Hooking the data sources up with the logbook.