Roman Numerals: Don't substitute d for 0 in add10

[malcolmsailor]

add10 annotations (which occur when converting some DCML files) were causing a bug because the 0 was being converted to o, leading to parsing exceptions.

This PR updates the replace logic for 0 so as not to match this case, and adds a test case to the unit test.

[coveralls]

coverage: 93.036%. remained the same when pulling 89e0b5a on malcolmsailor:preserve-10-in-figures into 8baa273 on cuthbertLab:master.

[jacobtylerwalls]

Thanks for the fix and test!

[jacobtylerwalls]

For future work with regexes, esp. in such a common code path like RN instantiation, it would be good to do timing tests when considering alternatives. I think without the lookbehind you can get an improvement:

>>> from timeit import timeit
>>> timeit("re.sub(r'(?<!\d)0', 'o', 'viio7')", setup='import re')
0.37872337497537956
>>> timeit("re.sub(r'(\\D)0', r'\1o', 'viio7')", setup='import re')
0.324621667037718
>>> timeit("re.sub(r'(?<!\d)0', 'o', 'vii07')", setup='import re')
0.43934187496779487
>>> timeit("re.sub(r'(\\D)0', r'\1o', 'vii07')", setup='import re')
0.3506033340236172

[malcolmsailor]

If we're worried about speed perhaps it's worth doing a simple membership check to see if 0 is in the string. With a test where half of the figures contain 0 we get ~50% speedup; since 0 is presumably less common than that in a more representative sample of chord figures we'd probably get a much larger speedup.

In [8]: import re
   ...: from timeit import timeit
   ...: 
   ...: 
   ...: def f(fig):
   ...:     if "0" in fig:
   ...:         fig = re.sub(r"(\\D)0", r"\1o", fig)
   ...:     return fig
   ...: 

In [9]: def g(fig):
   ...:     return re.sub(r"(\\D)0", r"\1o", fig)

In [10]: timeit(
    ...:     "[f(fig) for fig in ['I', 'viio7', 'vii07', 'V[add10]']]",
    ...:     setup="from __main__ import f",
    ...: )
Out[10]: 1.833819167004549

In [11]: timeit(
    ...:     "[g(fig) for fig in ['I', 'viio7', 'vii07', 'V[add10]']]",
    ...:     setup="from __main__ import g",
    ...: )
Out[11]: 3.177722458000062