Any object reference inside this function is treated as hidden to
exclude it from dependency calculation. This function allows some form
of cyclic depdenency.
Merger note: renamed from "HREF" to "HIDDENREF" to avoid confusion with
the standard "hypertext reference" use of HREF.
Based on the information from bunch of the latest supported distros:
Debian Jessie: 1.55
Debian Stretch: 1.62
Ubuntu 16.04: 1.58
Ubuntu 18.04: 1.65
Fedora 31 and 32: 1.69
Redhat Enterprise Linux 8: 1.66 (1.53 for EL-7, though)
openSuse Leap 15.1: 1.66
Found via `codespell -q 3 -L aci,ake,aline,alle,alledges,alocation,als,ang,anid,ba,beginn,behaviour,bloaded,byteorder,calculater,cancelled,cancelling,cas,cascade,centimetre,childs,colour,colours,commen,currenty,dof,doubleclick,dum,eiter,elemente,feld,freez,hist,iff,indicies,initialisation,initialise,initialised,initialises,initialisiert,ist,kilometre,lod,mantatory,methode,metres,millimetre,modell,nd,noe,normale,normaly,nto,numer,oder,orgin,orginx,orginy,ot,pard,pres,programm,que,recurrance,rougly,seperator,serie,sinc,strack,substraction,te,thist,thru,tread,uint,unter,vertexes,wallthickness,whitespaces -S ./.git,*.po,*.ts,./ChangeLog.txt,./src/3rdParty,./src/Mod/Assembly/App/opendcm,./src/CXX,./src/zipios++,./src/Base/swig*,./src/Mod/Robot/App/kdl_cp,./src/Mod/Import/App/SCL,./src/WindowsInstaller,./src/Doc/FreeCAD.uml`
PropertyExpressionEngine is changed to derived from a new class
PropertyExpressionContainer, which is in turn derives from
PropertyXLinkContainer. This makes PropertyExpressionEngine a link type
property that is capable of external linking. It now uses the unified
link property APIs for dependency management and tracking of object
life time, re-labeling, etc.
ObjectIdentifier is modified to support sub-object reference, but is
not exposed to end-user, because expression syntax is kept mostly
unchanged, which will be submitted in future PR. There is, however,
one small change in expression syntax (ExpressionParser.y) to introduce
local property reference to avoid ambiguity mentioned in
FreeCAD/FreeCAD#1619
Modified Expression/ExpressionModifier interface to support various link
property API for link modification.
* Refactored code; moved mutable fields into a separate inner class.
* Added resolvedProperty to ResolveResults class.
* Set resolved document name, even if it does not resolve correctly, so we can give a better error message later.
* If the document name is explicitly set, and it does not resolve, don't try any further.
* If document name is set, use that instead of the ObjectIdentifier's owner when looking up the document object.
