Rename vtkArmatureWidget signals

See Issue #13733
Refactor create and node function

Make it return the ewly created node. The remove node from hierarchy is
also simplified to accept both node and positions.
This implies a change of the reparent function which beomes simplier and
safer.

See Issue #13616
Add parent control methods

It can be quite useful to know if a bone is directly parented or not with
a given parent.

See Issue #13616
Add merge bone method

This method allows the user to merge two bone that are parented (directly
or not) together.

Also comment out the vtkBoneWidgetTwoBonesTest.

See Issue #13616
Implement ShallowCopy() for bone representations

See Issue #13616
Harmonize enums values

Now all the enums have the same values for Rest mode and Pose mode.

See Issue #13733
Keep a bone representation in the armature

The armature has a bone representation from which all the bone
 representation are copied. This will help to have the same representation
throughout the armature.

See Issue #13733
Change Quaternion Macro

It is better to send back quaternions than double*.
Add a few normalize terms (normalization paranoia).

See Issue #13681
Fix Rest to Pose transition

The issue was that the local tail wasn't centered before applying
the RestToPoseRotation.

See Issue #13681
Implement DeepCopy()

This implies adding the method Set/GetAxesSize().
The DeepCopy enables the user to synchronized all the bones values
 together, including the variables not included in the API (most notably
the pose values).

See Issue #13681
Fix AlwaysOnTop

Otherwise it's never updated in the bones.

See Issue #13733
Fix Translation

The translation suffered the same effect than of issue #13615.
THis is fixed by adding the line handle for translation. This handle is
kept invisible in the code.

See Issue #13695
Refactor Callbacks

Using only one callback is enough.
Also correctly pairing the StartInteracionEvent and EndInteractionEvent
together.

See Issue #13610
Register BonesRepresentation

The BonesRepresentation should be registered by the armature using it.

See Issue #13733
Hide line handle

In out case, we only need the handle to compute the bone translation
correctly. In VTK (vtkPointHandleRepresentation3D) the handle visibility
is turned on when ComputeInteractionState() is called.
So in order to have an invisible handle, the hack is to set it to a size
zero.

See Issue #13695
Harmonize bone representation selected color

See Issue #13758
Update parenthood after placing tail

See Issue #13758
Use of appropriate term of DeepCopy()

ShallowCopy isn't the appropriate term here since all the properties are
duplicated in the representation.

See Issue #13733
Clean vtkBoneWidgetRepresentationAndInteractionTest

The vtkBoneWidgetRepresentationAndInteractionTest needed cleaning. Note
that this is only preliminary work and this test is really more of an
example than a test right now. It will need more work to become a test.

See Issue #13720
Clean and Rename test

The vtkBoneWidgetTwoBonesTestRotationMatrixTest needed cleaning. It was
not doing was its name intended either so it was renamed. Note
that this is only preliminary work and this test is really more of an
example than a test right now. It will need more work to become a test.

See Issue #13720