Set sixthMinor and seventhMinor to CAUTIONARY in romanNumeralFromChord()

[jacobtylerwalls]

Fixes #1217
Fixes #1229

FYI @napulen what do you think?

Clarification: this does not change any default behavior of figure or pitch parsing, but simply sets the attributes on the created RomanNumeral object to reflect how the figure should be interpreted, given the figure it was created with. (i.e., the method creates a cautionary "b" in "bVI", so set sixthMinor to CAUTIONARY.)

[coveralls]

Coverage remained the same at 93.241% when pulling 38c3a79 on figure-roundtrip into d73e6b7 on master.

[napulen]

Looks good! I have a long corpus of RomanText files, let me try it there and confirm whether the issue is fixed after this.

[napulen]

(running this corpus test later today)

[napulen]

OK, I can confirm that these default attributes of the RomanNumeral object mimic the parsing behavior of the RomanText files I have been using.

Thanks, @jacobtylerwalls!

[mscuthbert]

Thanks all for this improvement without introducing (much) backwards incompatibility.