V7 bugfix

Fixed bug in z coordinates that was stopping preview extending lines to cutter edge properly.
See v7.0.0.0 for updated files.

Significant update including aligning swept wings

Version 7 is primarily around usability and flexibility. It includes:
• Various bug-fixes from 6.1 release.
• Ability to take forward and reverse cuts and separate cutting top and bottom surfaces.
• Revised wing dialog to reduce clicks and show root and tip sections
• Zero length moves filtered out of G-Code
• Cut documents can be created from plot documents and vice versa (useful if you want to plot a few ribs on paper in conjunction with cutting a core).
• Now pays attention to the closed flag in DXF LWPolyLine import.
• Optionally optimises G-Code output when plotting a wing. Results in smaller G-Code files.
• Block (plan) view of cutter and foam block. Useful for visualising tapered/swept wings.
• Tapered wings can now be aligned by leading or trailing edge.

Provides G-Code compatibility with Mach3

Initial production (non-source) release. Provides a complete toolchain from specifying the sections and structure to driving steppers using a Teensy3.2 microcontroller and Arduino.