Fix and test for bug #287
Added crude support for test result storage and comparison.
Clean up old test files.
Archive materials of old test framework
Test and fix (plus some support stuff) for #288
Fix and test for #291
Fix and test for #292
Fix and test for #293
Fix and test for #295
Update result file. State only added to POs if it exists now.
Tweak Playground for easier work with result files.
Added fix and test for #296
Test and fix for #299
Record types for VDM-SL state should include an invariant, fixes #304
Fix problem with nil fields in sync clause expressions, fixes #302
Correct guards for static operations and variables
Correction to listener handling in value assignments
Prevent inheritance of private constructors, fixes #7
Merge commit '23b664c2306291160867c4b54c16730ab14018e3' into test