correct 3 tests and temporarily removed outdated tests from test scope, this tests need an update with the new data handlers

moved helpers into new location, this is a commit only on the already finished doc strings, tests fail potentially fail with this part-wise commit

introduce 'compile_options' in model_class which combines all allowed args of keras' .compile() methods. The method 'set_compile_options' has to be defined in child class if additional compile options should be used (optimizer and loss, have to be set anyway in child.__init__ #110