FreeCAD v0.20.28870 git master + FreeCAD linkstage3 git master

this release contains my latest build of FreeCAD using the latest upstream master branch +1 commit to fix the mac app bundling. Also, included in this release is a build of realthunder's linkstage3 fork of FreeCAD.

A couple of notes about these releases

• these releases were built on macos catalina using intel and should run on any current macos or newer, intel and ARM (rosetta2 required)
• i built coin3d and pivy from git master head using [email protected]
• i built pyside2 & shiboken2 using [email protected]
• i built boost-python using [email protected]
• i unlinked upstream homebrew/core, tbb, opencascade, and vtk. so i ended up building and linking against the below versions
  • vtk 8.2
  • opencascade 7.5.3
  • tbb@2020

i used the above versions of those formula/packages because i was unable to build realthunders fork using the upstream counterparts

when using multiple versions of freecad on the same box, something i've noticed is loading the different takes a little longer to launch initially, but sticking with that version subsquent launches should be quicker. this process starts again, ie. switching from upstream master to linkstage3

sha256sum FreeCAD-0.20-git-master.dmg
bda967813059e18be989787999f9af2c9c286ffd2c5110ec1b8cba4f81ca4500  FreeCAD-0.20-git-master.dmg

sha256sum FreeCAD-linkstage3-git-master.dmg
b612f677ac898504e419fb4055b26d27e6d08418356b89bcb130e8e85c58e9cf  FreeCAD-linkstage3-git-master.dmg