[ENC] Reproducible + automatic tests

[stannam]

re: #498
PCT tests are living in ./tests
Test and update these tests to make sure they actually work.

[stannam]

• go through all the tests
• need to modernize data files under ./tests/data to cover more use case scenarios (e.g., homophones behaviour, syllabified corpus, etc)
• cf. Travis CI is not free anymore and so we need migration if we want to automate continuous testing.