Spent a day stuffing around with the exporter and marlin firmware to figure...

Spent a day stuffing around with the exporter and marlin firmware to figure out why pronterface was throwing checksum errors when
sending lots of G02 and G03 arc vector cuts. It turns out that with too much precision in the cuts marlin's buffer fills up and it's
unable to receive any more serial data. I resolved this by reducing the float point precision down to 3 decimal places and shifting
power and pulse settings to the G00 move command that comes before a set of G01, G02 and G03 commands to limit data that's needed to
be sent over the wire.

I also fixed up the part of the exporter to allow the offset and scaling functions to work. Though I found that looking at the scaling
code it will only scale from the original 0,0 coordinate, it doesn't scale based on a centre point.

I was able to burn vector gcode files with 10000 lines without issue, 30 minute burns with no checksum errors reported by Marlin.