DeepSOIC6

Made soon after critical fixes to expression support were merged.

Compared to master FreeCAD, this branch features:

• unlimited external geometry linking in Sketcher, with circular dependency prevention detection
• preliminary sketch attachment support (outdated - much more powerful attachment is now in PartDesign Next)

Installation:

1. download zip, unpack, run bin/FreeCAD.exe
2. if it doesn't run, download and install Microsoft Visual C 2013 redistributable (select 64-bit version).