v0.12.1: added some more CMOS examples

- added a fuse to simulate a PROM or PAL.
- added some more CMOS examples
- Improved flexibility of the splitter.

v0.12: Added undo/redo

- Added undo/redo functions.
- New wire drawing mode: If a wire is added it is rectangular by default.
  In rectangular mode "F" flips the wire and pressing "D" switches to diagonal mode.
- Added inverted inputs for basic gates and flip-flops.
- Added a locked mode, which avoids the unwanted modification of the circuit.
- Better support for high dpi screens.
- Added DIL packages to allow more "physical" circuits. See examples/74xx.
  Up to now only a view 74xx circuits are available.
- Added a pin number attribute to inputs and outputs.
- Add some functions to make it easier to create 74xx circuits.
- Lots of small usability improvements.
- Added a list of keyboard shortcuts to the documentation.

v0.11.1: Some minor bug fixes

- Added the possibility to open a circuit from the command line.
- The backspace key works like the delete key.
- Avoid extreme long lines in the error message dialog.
- Some minor bug fixes.

v0.11: Added floating gate FETs

- Added floating gate FETs.
- Better detecting of missing signals in test cases.
- Better plausibility checks if diodes are used.
- Added a loop command to the test data parser.
  See "cmos/sram.dig" as an example usage of the new loop statement.

v0.10: Added switches and FETs

- User can select the expressions representation format in the settings dialog.
- Better formatting of minimized expressions.
- Easier editing of truth tables
- Mouse actions can be canceled by the ESC key.
- With CTRL + mouse button you can now select and move/delete wires.
- Added a real bidirectional switch and a relay.
- Added N and P channel FETs and some CMOS examples, including a 16 bit SRAM
- Added a rotary encoder
- Added a LED matrix display
- Improved and documented the file import strategy.
- Added a tree view to insert components.
- Added support for the ATF1502 and ATF1504 CPLDs.
- some minor bug fixes

v0.9: improved documentation

- improved documentation
- moved "show listing" functions to the assembly IDE.
- rearrangement of the components in the components menu
- made "don't care" as test case input values functional
- added a better test data parser which supports a "repeat([n])" statement.
  See the "combinatorial/FullAdderCLA.dig" as an example usage of the new "repeat([n])" statement.
- cleanup of splitter behaviour in respect of high z inputs
- fixed an error that caused an exception if a circuit which directly connects an input to an output
  is used as embedded circuit.
- some minor bug fixes

v0.8: added support for PLDs

- added pull up & pull down resistors and programmable diodes
- added some PLD examples like a simple PLA and GAL
- added GND, VDD and a switch
- added a help dialog for components
- added a simple documentation viewable via the help menu
- fixed "sometimes unwanted start of drawing a wire" problem (hopefully)
- some minor bug fixes

v0.7: bug fixes and improved drawing speed

- fixed a bug which causes two HighZ values to be not equal during test execution.
- added double buffer to CircuitComponent to make it more responsive
- improved debugging of processors

v0.6: fixed sync issue

- fixed sync problems while drawing circuit
- added Conway's Game of Life example

v0.5: - creation of state machines with JK-flip-flops

- enabled creation of JEDEC and CUPL files for GAL16v8 and GAL22v10