[pt] Improve degree sign and ordinal indicator detection rules

[p-goulart]

Prob. still not perfect, but first let's get rid of the low-hanging fruit FPs:

• make a systematic distinction between temperature scales (which require a space before the degree sign) and cardinal points (which require the space between the degree and the abbreviation):

  • 90 °F but 90° N, 'noventa graus Fahrenheit' but 'noventa graus ao norte'.

• improve, somewhat, the recognition for coordinates like 90° 45′ 22″, using the prime/double prime characters for angular minutes/seconds, but this may require some more tinkering (and potentially also different tokenisation, which I'm not keen on...);

• crucially, I've added o to the ordinal/degree detection rule – the nightly corpus reveals many instances of 100o clearly indicating degrees; once this is working, the ORDINAL_ABBREVIATION rules should be easier to work with, as we will have eliminated many FPs (and these rules are, crucially, the last ones of this group to run!).

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^{As a small aside, users' habit of replacing the degree sign with lowercase o may come from some kind of automatic MS Word rule to convert that to the ordinal indicator after \d, since they, uh, look similar. It would be lovely to eliminate this habit somehow, and the first results on the live degree/ordinal rules show very high acceptance rates.}