Default GDML import units restored to Geant4 ones. Can be changed before import using TGeoManager::SetDefaultRootUnits().

Looks like only TGeoCone was ignoring name.
Fixes error described in https://root-forum.cern.ch/t/32493

The test stressgeometry fails with a crash in
TGeoVoxelFinder::GetValidExtra() if -O3 or -Ofast is used.

This commit fixes navigation in overlapping nodes when the point is
close to the boundary. See also:
https://root-forum.cern.ch/t/unexpected-navigation-behaviour-with-overlapping-nodes/26618

Added GDML support for: opticalsurface, skinsurface, bordersurface, matrix, property, including test macro

This reverts commit 10025483.

This reverts commit 9b8c396d.

This reverts commit e160cd3e.

This reverts commit c71e9ade.

This reverts commit 922b53cf.

This reverts commit 7bc58016.

Otherwise, combining geocad headers leads to inconsistent definitions of Handle.

Otherwise we get compilation errors:
In file included from /usr/include/oce/Handle_Interface_TypedValue.hxx:11:0,
                 from /usr/include/oce/Handle_Interface_Static.hxx:11,
                 from /usr/include/oce/Interface_Static.hxx:11,
                 from /mnt/build/jenkins/wsincr/LABEL/ROOT-centos7/SPEC/default/root/geom/geocad/src/TOCCToStep.cxx:38:
/usr/include/oce/Handle_MoniTool_TypedValue.hxx:14:27: error: aggregate ‘Handle Standard_Type’ has incomplete type and cannot be defined
 class Handle(Standard_Type);
                           ^

* List all headers and sources
* Restrict includes to target
* Avoid shadow and extra warnings from OpenCascade