Add test files for different versions of Protégé and test canonization

[CasperWA]

While the "truth" of ontologies is considered to be the set of triples, the difference in Turtle file generation of different Protégé versions might do some basic reasoning differently, resulting in a core difficulty in canonization between some versions.

This needs to be tested by for example utilizing the test files introduced in #15 and load and re-save them using different Protégé versions to understand what the differences might be. As the ultimate goal of this application is to canonize especially Protégé-generated Turtle files, extra care will be taken to try to accommodate this goal.