Non-planar G1

Hi,

Maybe it's intended, but the plugin seems to silently ignore Gcode files with an arbitrary 3d set of segments, like:

G90
G21
G92 E0
G1 F1800.0
G1 X30.000 Y0.000 Z0.000 E0.00000
G1 X29.993 Y0.628 Z0.001 E0.02351
G1 X29.973 Y1.256 Z0.001 E0.04702
.............
G92 E0
