Merge branch 'ELASTIX-24-Component-Interface-Handshake' of https://github.com/kaspermarstal/SuperElastix into ELASTIX-24-Component-Interface-Handshake

Conflicts:
	Modules/Core/ComponentInterface/GDOptimizer4thPartyComponent.cxx
	Modules/Core/ComponentInterface/Interfaces.hxx

The new Travis infrastructure supports a new version of CMake which is
required by some of SuperBuild dependencies.

Model the GoogleTest build after SimpleITK. This fixes previous build
errors.

casts for the handshape are put in the acceptor generalized.

The functionality lives outside of the elastix project and serves as
toy example / prototype, without being complicated by ITK compatibility.

ENH: ELASTIX-9 Only access connections via component indexes; BUG: ELASTIX-9 ComponentExist() did not work

The ENH: We deliberately avoid using connection indexes, but instead
force the user to think in terms of components which is conceptually
simpler and results in less pointers being thrown around while
constructing the blueprint.

The BUG: Temporarily disable functionality for deleting component until
we find a god way of asserting that vertex exist before it is accessed.