Settings: Makerbot start- and endcode

[peteruithoven]

Because the Makerbot speaks another language we need specific start and end code.

We should try to only show one set at the same time, so or the Marlin codes or the Makerbot codes. We could do this according to the printer selection or a radio button closer to the start end code settings.

It is tempting to save settings per printer type, but this be much more complicated.

[peteruithoven]

Done. In the settings I added another fieldset for X3G start- and endcode.
Only the appropriate start- and endcode are shown according to the selected printer type.
The appropriate codes are used during gcode generation. But... that does mean X3G code is combined with the regular generated gcode.