0.8.22:

* Field Definitions:
  - Do not save empty default values as "NULL" or 0.
  - Prevent crash when opening Field details a second 
    time.
  - Allow saving when the default value changes.
  - Calculated fields:
    - Simplified python API.
    - Aggregate calculations (sum, count, max, min) 
      on related records.
    - Calculated fields may use the results of 
      other calculated fields.
    - Do not lose digits after decimal points.
    (Demonstrated in the Invoice table in the example.)
* List:
  - Really do lookups and recalculations when 
  adding new records.
* Details:
  - Related records: Only show related records, not 
    all records.
* g++ 3.4 build fixes.