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