Fixed:
1. Export only one segment when offsetting outward.
2. Supported MacOS 10.13
3. Unexpected backend waring when starting.
4. Paste would executed twice sometimes.
5. Wrong Layer name when importing sag made by Inkscape by layer .
6. Flipping bug when importing dxf.
7. Unexpected slow speed when moving to first point of engraving.
8. Wrong focus adjusting height.
Added:
1. Support ai, pdf files.