Add option to compile *ino files additionally to '.cpp

[luni64]

Suggested by @WMXZ-EU

https://forum.pjrc.com/threads/57245-VisualTeensy-upgraded-to-support-Teensy-4-projects?p=232318&viewfull=1#post232318

Might be good to have a warning/info explaining that the *ino has to be c++ standard compliant