Add support for point set

See merge request !202

Mesh class is renamed to PointSet since
the word 'mesh' implies that connectivity
information is part of the class which is
not the case

Modify PBD class to allow a point set to be used
for fluid simulations

Point set (Mesh) is now a full and renderable class.
Scene objects can now be created that can utilize mesh
class for both physics and rendering.

A separate render delegate is created for Mesh class

BUG: Fixes the bug with tetrahedral rendering of deformable body

See merge request !201

ENH: Adds background color option to VTKViewer class

See merge request !200

Adds background color option to VTKViewer class which
internally calls vtkRenderer

ENH: Fix winding order of surface mesh to enforce consistency

See merge request !198

Add option to enforce consistency of winding of resulting surface mesh in the extractSurfaceMesh function

Start with a reference triangle and enforce the consistency of its neighbors.
Keep track of those neighbor triangles whose order is enforced but its neighbors not necessarily enforced (trianglesCorrected).
Continue this operation until there is no triangle left in this list.

ENH: Add viscous damping to the PBD model

See merge request !199

STYLE: Make device names in sandbox global variables

See merge request !195

Move the main() to the end of the file

BUG: Fix lighting related bugs in fluid examples

See merge request !194

Custom shaders

See merge request !173

Pbd fluid simulation

See merge request !190

In the PbdConstantDensityConstraint class:
1. Style changes
2. Remove unused functions
3. Remove casting warnings
4. Add get set functions for density and max. neighbor distance
5. Add comments for variables and functions
6. Remove grid based neighbor search functions

PERF: Remove cell consistency check

See merge request !193

DOC: expanding section about use of uncrustify

See merge request !175

The cell consistency check takes considerable time during the initialization
and is removed from the surfaceMeshRenderDelegate.

Mesh related checks such as this (watertightness etc.) should be done
within the utility functions of Mesh or Rendering module. For now the user
is expected to supply correct meshes.

STYLE: Clear uncrustify test failure errors

See merge request !191

BUG: Do not scale the cylinder based on radius

See merge request !189

BUG: Do not set the object controller offsets from the objects

See merge request !187

Add visibility on/off option for rendered object

See merge request !186