Support receiving longer MIDI sysex on Teensy 3.1+

teensy3/usb_midi.c

 uint8_t usb_midi_msg_data1;
 uint8_t usb_midi_msg_data2;
 uint8_t usb_midi_msg_sysex[USB_MIDI_SYSEX_MAX];
-uint8_t usb_midi_msg_sysex_len;
+uint16_t usb_midi_msg_sysex_len;
 void (*usb_midi_handleNoteOff)(uint8_t ch, uint8_t note, uint8_t vel) = NULL;
 void (*usb_midi_handleNoteOn)(uint8_t ch, uint8_t note, uint8_t vel) = NULL;
 void (*usb_midi_handleVelocityChange)(uint8_t ch, uint8_t note, uint8_t vel) = NULL;
 		if (type1 >= 0x06) sysex_byte(n >> 16);
 		if (type1 == 0x07) sysex_byte(n >> 24);
 		usb_midi_msg_data1 = usb_midi_msg_sysex_len;
+		usb_midi_msg_data2 = usb_midi_msg_sysex_len >> 8;
 		usb_midi_msg_sysex_len = 0;
 		usb_midi_msg_type = 7;				// 7 = Sys Ex
 		if (usb_midi_handleSysEx)

teensy3/usb_midi.h

 #define SystemExclusive 7
 */
 
-#define USB_MIDI_SYSEX_MAX 60  // maximum sysex length we can receive
+// maximum sysex length we can receive
+#if defined(__MKL26Z64__) || defined(__MK20DX128__)
+#define USB_MIDI_SYSEX_MAX  60
+#else
+#define USB_MIDI_SYSEX_MAX 290
+#endif
 
 // C language implementation
 #ifdef __cplusplus
 extern uint8_t usb_midi_msg_data1;
 extern uint8_t usb_midi_msg_data2;
 extern uint8_t usb_midi_msg_sysex[USB_MIDI_SYSEX_MAX];
-extern uint8_t usb_midi_msg_sysex_len;
+extern uint16_t usb_midi_msg_sysex_len;
 extern void (*usb_midi_handleNoteOff)(uint8_t ch, uint8_t note, uint8_t vel);
 extern void (*usb_midi_handleNoteOn)(uint8_t ch, uint8_t note, uint8_t vel);
 extern void (*usb_midi_handleVelocityChange)(uint8_t ch, uint8_t note, uint8_t vel);