Add Chip45's Crumb128 V5.0 AVR ATmega Module

[qcho]

I'm working with a Crumb128. Loving PlatformIO but doesn't have the Chip45 boards we are using.

I'm only pushing the "Crumb128 V5.0 AVR" since it's the only i could test. But the naming convention of chip45_crumb128v50 will allow to add all of them in the future.

Hope it get's merged so I don't have to pass this json up everytime ^_^

[MCUdude]

I don't quite see why there would be any need for a dedicated Crump128 board when there exists a generic ATmega128 option where you can tweak the platformio.ini file to do exactly what you want. See MCUdude/MegaCore/PlatformIO.md for a nice template you can use.