Fix friend classes persistification and concurrent access to add() method

See merge request !9

Briefly: I added locks to protect the methods that access the m_daughters std::vector. However, having the lock to protect the .size() call before launching exec() causes a deadlock. I think we should think more thoroughly about the correct way to make this class, and its sibling GeoFullPhysVol, thread-safe.

The GeoPhysVol::add() method adds a child to a GeoPhysVol.
The underlaying method which increases the number of children (RCBase::Ref()) is thread-safe
because the counter is implemented with a std::atomic. But the vector storing the children
of a GeoPhysVol is not thread-safe because the access to its members is not protected in any way.
I added a mutex and locks to all methods writing to or reading from the vector.

In C++ >= 11, the friend class declaration when the friend class is typedef-ed
must use a simple-type-specifier instead of an elaborated-type-specifier.

Ref: https://community.ibm.com/community/user/ibmz-and-linuxone/blogs/fang-lu2/2020/03/24/introduction-to-the-c11-feature-extended-friend-declaration?

Provide access to boolean shape object operands

See merge request !8

Revert "Adding back handleLArCustom() to GeoShapeAction."

See merge request !7

This reverts commit 4dc6f24a

This is needed to fix the Athena master build. When removing the LArCustomShape from GeoModelIO, in fact, all occurences of LArCustomShape were removed from GeoModelKernel as well; but Athena still use them, in particular the handleLArCustom() method of the GeoShapeAction class.

For details:

- atlas/athena!31618 (comment 3321141)
- 62142525

Deprecation of custom shape and introduction of the GeoUnidentifiedShape

See merge request !6

Introduced first version of GeoVStore

See merge request !5

Revert "Update version number and Add installation RPATH settings. This fix installation problems on all platforms."

This reverts commit 9a2ad13e.

This reverts commit b759050c.

Update version number and Add installation RPATH settings. This fix installation problems on all platforms.

GeoModelKernel: Fix compilation warning.

See merge request !2

GeoGenericFunctions: Fix clang warnings.

See merge request !3

    
clang warnings: missing/inconsistent override keywords.

Unused variable.