screenkey 0.9

- Ctrl+Ctrl detection now works correctly in more scenarios.
- Ctrl++ (and similar sequences with repeated characters) are now shown as
  Ctrl+"+" for improved readability.
- Shift+Backspace is now recognized and shown correctly.
- Several multimedia keys are now supported. If "FontAwesome" is installed,
  the correct symbol is also displayed instead of a text abbreviation.
- Visualization of whitespace characters can now be controlled.
- Repeated key sequences are now abbreviated with a repeat count if above the
  specified threshold (3 by default).