Reliable detection of day-month combinations

[vmenger]

In #92 we removed detection of day-month combinations, and only detect combinations of day, month and year as date. Day-month combinations may still be considered PHI in some cases, however, detection is harder than a simple regexp. See e.g. these real-world examples:

Patient werd op 5/5 opgenomen
Patient werd op 2.5 opgenomen

versus:

Motoriek:  Deltoideus 5/5; Biceps 5/5
Start met bisoprolol 2.5 mg

Perhaps a different rule-based approach can be used here?