Fix position file output error in KiCAD 8.0

[fairkid-ai]

Due to API changes in KiCAD 8.0, the following changes must be made to comply with it.

1. footprint GetProperties() -> GetFields()
2. footprint GetOrientation() -> GetOrientationDegrees()
3. org_pt = pcbnew.VECTOR2I(org_pt.x, org_pt.y)

The changes keep compatibility to old versions.

Note that this patch only fixes position file output whereas the Gerber output still has errors in KiCAD 8.0.

Additional push:
Eventually, I removed the last error blockage in kicad cause I did not know what alternative function in 8.0 can help, as follows:

- popt.SetExcludeEdgeLayer(True)
+ if hasattr(popt, "SetExcludeEdgeLayer"):
+   popt.SetExcludeEdgeLayer(True)

The plugin eventually works in KiCAD 8.0.
Anyone find an alternative solution to exclude the edge layer in KiCAD 8.0, please pull request. Thank you!