Add fancy unit/math input to pad tool

Pad tool does not currently save the units, so the result is still in mm.
+ fixes #0000928: Change selection numbering base in the Sketcher from 0 to 1
+ expose zoomIn/zoomOut to Python
added way of breaking BSplines into line segments in Shape2DView
Draft: made last commit more backward-compatible
Merge remote-tracking branch 'refs/remotes/s7726-repo/PadToolDatum'
Fully implement Units in PartDesign Pad
Avoid OCC error for closed Draft.BSpline with same first/last points
Merge branch 'master' of ssh://git.code.sf.net/p/free-cad/code
Get node of face implementation
Finish get nodes by surface
PySide switch for LibPack >= 8.2 default on in the vanilla sourc

This means that you need 8.2 or higher or you have to switch of FREECAD_LIBPACK_USEPYSIDE!
Fix default bug in Pad dialog
Fix doulbe value entry in history of InpuField
First tests of using InputField via Python
Further implementing MechanicalAnalysis
+ fixes #0001375: FreeCAD does not support of pivy and shiboken in Libpack8.x
Merge branch 'master' of ssh://git.code.sf.net/p/free-cad/code
+ undo changes of 8b610aff on issue 0001375 because this was done in c7e41c
+ fixes #0001380: Allow to set user-defined names for constraints