Make compatible with Cura 5.6

[alexbdv]

Starting with Cura 5.6 (5.5 works) - invalid GCode will be generated unless the attached changes are made.

For example, setting bed temperature:

Old Config + Cura 5.5: M140 S120.0 T0 ; set bed temperature

Old Config + Cura 5.6: M140 S(120,0) T0 ; set bed temperature

Old Config + Cura 5.6: M140 S120 T0 ; set bed temperature

The "Old Config + Cura 5.6:" format will cause FFCP to ignore the command (and eventually start printing with cold bed + cold hotend).