ENH: implemented spatial hashing and added an abstract class

See merge request !147

BUG: Fix point plane cd

See merge request !154

ENH: Add capsule geometry, capsule-mesh collision and rendering

See merge request !149

Currently VTK doesn't support capsule actor.
vtkCapsuleSource class originally authored by
Johan Andruejol <johan.andruejol@kitware.com>
was modified and used. The source of vtkCapsuleSource
class is placed in the imstk source for the moment.
This has to be migrated to vtk proper in the future.

Adds capsule-point cloud collision detection.
First the each point in mesh is checked against
the bounding sphere of the capsule. If inside,
the closest point is found on the line joining
the two apexes of the capsule. If the point
is inside the bounding sphere then the closest
point should be inside the capsule. If the distance
between the closest point and the mesh point is less
than radius of the hemispheres of the capsule, the
collision is registered.

BUG: Fix mismatch of Libusb file hash during download

See merge request !151

Render imstk::HexahedralMesh in the scene

See merge request !146

Updates to make it compile with Visual Studio 2015

See merge request !148

Improved MSH reader for reading and generating a volumetric mesh of hexahedral type

See merge request !145

Add deformable rigid penalty collision

See merge request !128

Co-Authored-by: Alexis Girault <alexis.girault@kitware.com>

Adds deformable-rigid penalty collision handling. Unifies all the
penalty collision handling classes into one.

Co-Authored-by: Alexis Girault <alexis.girault@kitware.com>

 Add collision Mesh to sphere and plane coll. detection classes based on brute force approach.

Adds utility functions for creating scene objects with commonly used
call patterns

Co-Authored-by: Alexis Girault <alexis.girault@kitware.com>

ENH: Adds generalized linear projection constraints

See merge request !140

Generalizes linear projection constraints implementation.
Modifies testDeformableBody example to test the changes.

ENH: Allow custom library definition

See merge request !143

Expand the imstk_add_library cmake function by exposing the variables
H_FILES (headers) CPP_FILES (source) and SUBDIR_LIST (build interface
directories - the current source dir is always included).

If those values are not manually set, the previous behavior applies,
where all the files and directories in the root directory are used for
that target.

Used that new mechanism for the Rendering target to prepare for Vulkan
integration.

DATA_ROOT_PATH did not exist since the introduction of external data.
Save screenshots in runtime directory instead.

Correct warning: extra tokens at end of #else directive in
testCameraController

BUG Screen Capture utility incorrect initialization. Plus an example.

See merge request !139

Features from CameraNavigationV2 branch

See merge request !137