v0.21: Added an FSM editor and SVG import

- Added a simple SVG importer to define custom shapes.
- Added an FSM editor, which allows to input a FSM, creating a associated
  truth table and finally allows to create a circuit which implements the FSM.
- Added a divider component.
- Added signed multiplications.
- Wider shapes were added, to better match the IEEE shapes to the standard.
- Added a RGB-LED.
- Added IC 74189 and IC 74382 to the Library.
- Small improvements at the test case parser.