Get the number of characters using len(str(ADIF_VERSION)), rather than hard-coding it.
Clear up all the .adi files.
Move to version 0.1.

The main changes since v0.1b are:
- The ADIF export functionality has been fixed. Previously, only markers were being written and the actual record data was being skipped.
- The BEL character has been removed from the data received from the DX cluster.
- The 'Notes' column is no longer automatically resized.
- QSOs can now be sorted in the correct chronological order.