A surfaceMesh will not be automatically extracted when
reading a volumetricMesh due to the long time necessary
for that process, which will be improved later on.
(vtkDatasetSurfaceFilter is 100x faster)

The user will have to call computeAttachedSurfaceMesh to
extract the surface mesh from its volumetricMesh if he
needs it.

The way its done the outer loop will not be traversed fully all the time. Fixes this bug in surface mesh extraction function.

reads polydata and unstructured grid meshes

1) Clean up print methods
2) Put initialize, print, clear, getVolume on top
3) Add missing overrides
4) Replace extractSurfaceMesh by computeAttachedSurfaceMesh
5) Define Mesh::print
6) Use Mesh::clear in subclasses

Adds optimizer to the mesh. This algorithm rewires
the node order and triangle connectivity to optimize
for memory layout. Adds tests for the same.

The algorithm starts with a random node and flood-fills
in the triangular mesh space adds nodes and elements
at every iteration. The iteration ends when the surface
is "flooded". The algorithm assumes that the mesh is
one topologically connected entity.

TODO: Further optimization at each iteration. Extend to other mesh types.

Adds a function to check if a geometry is a mesh.
Adds printing to geometry class
Stylistic changes in extract mesh class

Fixes bugs and tests surface extraction.
Fixes bugs and tests one to one nodal map.

1) readAsAbstractPolyData completed
2) readAsGenericFormatData still ongoing
3) implemented standard createSurfaceMesh in MeshReader

- Add imstk::Mat4f and imstk::Mat4d
- Add imstk::MAX_D and imstk::MIN_D
- Remove 'Map' from GeometryMap functions
- Reorder functions in a consistent manner
- Correct reference returns
- remove unnecessary ismtk:: due to namespace
- rename vertex/triangle/hexadron/tetrahedron composed
methods with their plural form when needed
- follow style rule with return type on a line and
function name on the following one during declaration
- move print() to geometryMap base class and use it in
override functions
- use for each c++11 architecture when possible
- correct wrong iteration in HexahedralMesh::getVolume
- place conditions for return at the top of functions
- declare WeightsArray in TetrahedralMesh instead of
TetraTriangleMap
- Rename findEclosingTetrahedra to findEnclosingTetrahedra
- add override on virtual functions in child classes
- correct test function name in Sandbox

Minor fixes to returning references to locals in various places.

Adds tet-tri map and all the support functionality that it needs

Adds Tetra-Triangular mesh map.
TODO: Code check and add tests

(1) `SimulationManager::startSimulation()` will check if a Viewer is
already rendering, and will only start a rendering/interaction loop
in the main thread if it isn't. This allows us to work with two
possible cases:
(a) a QT Application with an existing widget for rendering, in which
case we do not want to control the rendering window ourself in a loop
(b) a standalone `vtkRenderWindow` application, in which case we do
want to create a window when our simulation starts and loop until the
window is closed.

(2) `SimulationManager::startSimulation()` can be launched with a debug
boolean option (off by default), which will allow to not automatically
simulate the dynamics of the scene, to be able to interact with the
scene beforehand (using the mouse).

(3) `imstk::InteractorStyle` is based on vtkInteractorStyle specifically
the trackballCamera and allows to ignore mouse events in simulation mode,
and uses key events to control the simulation:
's' : start simulation
'e' : end simulation
' ' (space) : pause/run simulation

(4) The `Viewer` class and the `InteractorStyle` class have been moved
to the `SimulationManager` module, since they are more drivers of the
application themselves.

(5) The 'Sandbox' example has been refactored to make it easier to test
autonomous tests, and updated to use the new driver architecture brought
with this commit.

- SIMULATION adds the object actors and set the
interactor style to no interactions.
- DEBUG adds additional actors to visualize
lights, the camera, axis, and set the interactor
style to trackball to interact with the scene.

Light still a WIP

Adds visual tests for Isometric mapping

Changes names of math constants

Uses imstk defined math constants

Adds geometry map base class and isometriMap
Signed-off-by: Sreekanth Arikatla <sreekanth.arikatla@kitware.com>

Can directly used to create visual objects.

Also use unordered_map in SimulationManager.

Was not applying the quaternion on the good side.

Uses a dummy implementation of imstkScene to test
a module execution in multithreading.