Reclassify first instrument in MusicXML import

[jacobtylerwalls]

Reclassify first instrument of part in MusicXML import

Previously
Previously, every first instrument was imported as an instrument.Instrument. The test updated here to check for oboe, clarinet, and horn instruments fails on master.

Now
Rely on the MIDI program rather than, say, a fromString() operation on the name, although this could be added later (for instance to change Piano to Soprano when a file used piano sounds rather than Choir Aahs).

Fixes #988

Future
import all instruments from part

[coveralls]

Coverage increased (+0.7%) to 93.019% when pulling f3366c6 on jacobtylerwalls:instrument-reclassify into cb7df63 on cuthbertLab:master.

[mscuthbert]

One-staff pianos are unlikely to be correct -- need to look at instrument name a bit more to get more plausible instruments.