Pronterface with support for Professional Firmware custom C-codes

Normal Pronterface will filter any non-standard Marlin G-codes, so if you try to use configuration files with C-codes, they will be removed and only the standard codes will be sent to the printer.

This release adds support for Professional Firmware custom C-codes:

https://github.com/mriscoc/Ender3V2S1/wiki/Custom-C-gcodes