musicxml2ly bug and fix

[Phillip Kirlin]

Hi,

I think I have found a bug in musicxml2ly and I also have a fix for it.

BUG: musicxml2ly only outputs major key signatures, not minor (or other modes). 
 The problem is in the python code that reads the MusicXML file.

FIX: in musicxml.py, change line 168 from

mode_node = self.get_maybe_exist_named_child ('mode')

to 

mode_node = key.get_maybe_exist_named_child ('mode')

This is my first bug fix; I've never contributed to the project before (though 
I've been using Lilypond), so I hope I've provided enough information.  I 
thought this was too small as to warrant creating a whole patch, I figured a 
higher-up could just go change that line.

Hope this helps.

--Phil Kirlin