Pronsole should not load custom button definitions from config file during start

[DivingDuck]

Pronsole try to read custom button definitions form the config file if a user define those in Pronterface. This will lead to warning messages in the terminal window of Pronsole for each defined button in the config file:

"*** Unknown syntax: button 45 "Extruder FastExtr+775" /c "#ED353E" G91 G1 E775.0 F4000"