Tighten regex for floats
Tighten regex for floats

You're no longer allowed to type multiple radices, for instance.

Contributes to issue CURA-3157.

Curahelper/Cura,hmflash/Cura,ynotstartups/Wanhao,fieldOfView/Cura,Curahelper/Cura,ynotstartups/Wanhao,hmflash/Cura,fieldOfView/Cura