Gui: separate quarter as a separate library

[ppphp]

It is my question why package like Quarter is compiled with the whole Gui library, and library like Gui should also be separated into some submodule so that FreeCAD does not rely too much on a single package like OCCT, coin3d, or Qt.

[FEA-eng]

Looks like a desired but also quite big change. Someone should review this. Maybe @wwmayer could take a look?

[wwmayer]

There are many differences between the forked Quarter code in FreeCAD and the upstream version of the Coin3D project. Now by moving the code to a separate library using the same library name as the original can cause problems for people who use pivy because the two libraries are not binary compatible. The result will lead to unexpected failures or even random crashes.

[ppphp]

There are many differences between the forked Quarter code in FreeCAD and the upstream version of the Coin3D project. Now by moving the code to a separate library using the same library name as the original can cause problems for people who use pivy because the two libraries are not binary compatible. The result will lead to unexpected failures or even random crashes.

OK, I will try making binary compatible.