Adds time integrator which only sets rules for finite difference in time.
Adds comments for DeformableObject class

Usefull for when VRPN servers allows to add multiple devices.

Implement testTwoFalcons example to illustrate use of
two novint falcons.

1) for camera controller, setup offsets in initModule
based on the camera transform

2) for object controller, setup offset in sceneManager
initModule based on the object colliding geometry transform

This API allows the user to only worry about the geometries
and camera transforms, and let the controllers auto-init based
on that information when the simulation starts only.

Default value is 0 if not set (close to 1ms)

Reset sceneManager loop delay to 0 (fast loop)
and remove LOG info to avoid too much printing.

1) collidingobject needs to be virtual
2) trackingController was not passing scaling value

Subclass of trackingcontroller and collidingobject

Just like camera.

Used for camera controller, will be used for virtual tool
object. Useful to take care of world transformations (scaling,
offset, inverse translation, mirror rotations)

Adds memory.h for windows in cameraController to clear compiler errors

Adds close viewer window with esc button..

1) public constructor
2) add inversion flags
3) apply correct offsets and scales

still need to apply rotation offset based on
camera initial orientation

1) Camera does not hold a vtkCamera anymore (less tight integration).
It holds camera parameters.

2) Camera has a pointer to CameraController, that you can set up
based on a deviceclient. This camera controller has a reference
to the camera, and updates its parameters based on the deviceclient
retrieved information.

3) Scene runs the controller as an asynchronous module in its own
thread, it is therefore started in Scene::initModule and ended in
Scene::cleanUpModule.

4) In the timer loop of InteractorStyle, the vtk camera is updated
based on the scene camera.

5) In Renderer, a new vtk Camera needs to be created to match the
scene camera, since it is not created anymore in imstk::Camera.

1) Create a timer on the renderWindowInteractor
2) Render() in 'InteractorStyle::OnTimer()'

PR: https://github.com/libnifalcon/libnifalcon/pull/46

Based on improve-cmake that was merged:
https://github.com/libnifalcon/libnifalcon/pull/43

Did not support colors in standard output,
use std::cout and std::cerr instead.

Was not passed to external projects

The following warning on Linux and Windows triggers an error on Mac:

'''
imstkTetrahedralMesh.cpp:151: error:
non-constant-expression cannot be narrowed from type 'int' to 'value_type'
(aka 'unsigned long') in initializer list [-Wc++11-narrowing]
surfaceTri.push_back(triArray{ { a, b, c } });
                                 ^  ^  ^
'''

Fixed by using size_t where needed.

LibNiFalcon is an external project dependency on every system.

On Mac and Linux, libusb1 would be found
with other names.

Needed for VRPN. Use fork made for cmake improvements
and plan for a pull request:
https://github.com/agirault/libnifalcon/tree/improve-cmake

Could not link against hidapi on windows (setupapi)

Not sure about the need for libusb1 on windows.

Comments added to FindVRPN to analyze what is happening.