More tests(better coverage)
add tests and add test suite
Also show warnings (means all instead just errors)
Semantic Analyser: Bug fixes.

* Prepare to only use the interface in tests.
* Do not allow string+string.
* Allow a=b if lub(a, b) = type(a).
* Ignore assignments in while-loop.
* Detect assignments in if/else.
added protocoll from 06.06.2013
redesigned the abstraction of tokens
Merge branch 'master' into parser