Error handling rework
requested to merge 1629580/code:replace_error-system_with_exceptions into merge-25-replace-error-system-with-exceptions
**Replaced error-system with python idiom for error handling: exceptions.
Added funcitons to display error,warning,debug and info messages differently.**
Generel functionality is tested and everything is working fine so far, but not every error case was tested.
Edited by René