New 20170501 MegaDrumManager versions released

The latest MegaDrumManager version is now 20170501.

This version makes a major improvement to Sysex communication:

1. MegaDrum Manager now uses maximum speed possible even if SysEx delay is set very high.

2. Better detection of incomplete/incorrect communication.

3. It doesn't try to get/send settings from/to MegaDrum if MIDI ports are not open.