Arduino MIDI Library v5.0.1

This release fixes Software Thru being enabled by default in non-Serial transports.

Software Thru forwards received messages to the MIDI output, it's useful for serial MIDI to simulate the action of a hardware Thru port, but can cause problems if enabled for USB, BLE or other non-serial transports, where the MIDI stream would feedback to the computer. Therefore, SoftThru is only active by default on Serial transports (HardwareSerial and SoftwareSerial).