Misconversion of words like C.O.D.

[oshindow]

Hi!

Thanks for your work. I am using the convert function in transcribe.py.

It seems that word C.O.D. exist in CMUdict around Line 16930 C.O.D. S IY1 OW1 D IY1, but the convert function can not covert C.O.D. because preserve_punc function treat word C.O.D. as ["", "C.O.D", "."].

Obversiouly, C.O.D not in CMUdict, so the result is c.o.d*.

We can add some codes in preserve_punc function for dealing with this special case.