Incremental Parser Stability (#103)

[StephanErb]

This is a bug to track progress the current list of failing incremental parser tests.

As it stands we have 74 tests of which 11 are failing.

Mind that TestParsingScenarios only checks for crashes. It should be enhanced to return a status report about deleted and created modelelements. This can be done by comparing the old an and new textblocks model.

From the perspective of testcoverage, we seem to lack tests which use alternatvies and conditionals, especially nested alternatives.

[StephanErb]

We do now have 7 failures in 83 testcases. 4 of these failures are due to a simple re-use check that asserts that the root object was not replaced by a new one. This check is as basic as it can get.

We do still lack test coverage for conditionals and alternatives. Once we have implement these and dropped some dead parser/lexer code, we can expect the branch coverage to be fairly reasonable.

[StephanErb]

We have gone a long way but are not there yet. We are now, after merging pull request #128, down to two failing testcases. However, working within an editor shows that there seem to be more stability issues.