C2MS13 — mnemonic.n.sample.m.quality seems to be wrong type

In the messages where it exists, mnemonic.n.sample.m.quality is of type Boolean, with False meaning Good Quality and True meaning Questionable Quality. This just seems wrong. Probably should be a U16 with 1 = good and 0 = questionable.

The following notes were made when originally deferring it:
"This proposal changes the data type to signed 16 bit. And redefines GOOD as any non-negative value. BAD then become any negative value. Although this breaks the original slightly (0 is GOOD, 1 is BAD) ... it also allows for an expansion by implementations on kinds of good quality and kinds of bad quality without requiring the basic implementation to do anything more than report GOOD >= 0, or BAD < 0 by default. CAUTION: this is NOT backwards compatible. alternate approach would be BAD >= 1, and GOOD <= 0 – although this means some "goods" may be negative. this is not what is being proposed and is only a note."