tidy things up
fix messed up metric columns

don't know when this happened but thesis is correct
re-implemented the structure to hold table changes over version

- move related classes to new package
- the structure is now one for both sizes and changes
- move parsing and diffing to a new swing thread
- add a new file export containing all table metrics
alter to string
upgrade antlr and parsers to 4.4
fix parsing wrong schema
fix exports
catch tree expansion exceptions (fix #6)
proper way to get the filename (fix #3)