Midi fixes

Midi fixes agreed from last PR

Author: samg7b5

mingus/midi/midi_file_in.py

@@ -333,6 +333,12 @@ def parse_midi_event(self, fp):
                 raise IOError("Couldn't read MIDI event parameters from file.")
             param1 = self.bytes_to_int(param1)
             param2 = self.bytes_to_int(param2)
+
+            # "It is common for a note on with 0 velocity to be interpreted as NOTE OFF." https://stackoverflow.com/questions/48687756/midi-note-on-event-without-off-event
+            # this should resolve Lilypond midi files which don't seem to use ec 8 to signify NOTE OFF
+            if param2 == 0:
+                event_type = 8
+
             return (
                 {
                     "event": event_type,

mingus/midi/midi_track.py

@@ -236,7 +236,7 @@ def set_key(self, key="C"):
 
     def key_signature_event(self, key="C"):
         """Return the bytes for a key signature event."""
-        if key.islower():
+        if str(key).islower():
             val = minor_keys.index(key) - 7
             mode = b"\x01"
         else: