Convert Staff Text to Fingerings

EDIT2: added startCmd endCmd wrapper needed by MU4
EDIT: This new version no longer requires that every note has a legit stafftext & vice versa

A user (https://musescore.org/en/node/360098) requested the ability to convert Staff Text to fingerings in guitar scores. This MU3.x plugin does that. It may, or may not, run on MU4 (it has SmartQuit & Component.onCompleted).

Limitations:
one staff only
all notes must have a legit stafftext (0-5), and vice versa.

To customize legit stafftext edit var filter in the code in a plain text editor