MODSERIAL with support for more devices

Dependents:   1D-Pong BMT-K9_encoder BMT-K9-Regelaar programma_filter ... more

This pull request has been accepted and merged in by Erik -

I have added support for the Nucleo F746ZG

Let me know if there are any changes you think I should make. I have tested the library on Nucleo F746ZG and it seems to work just fine.

MODSERIAL with support for more devices Buffered, MODSERIAL, Serial