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

BUG: Fix camera controller

See merge request !129

COMP: Fix missing data added from !135

See merge request !138

Mistakes following the addition of more ExternalData from merged PR:
iMSTK/iMSTK!135

CDash: http://my.cdash.org/viewBuildError.php?buildid=1143408

ENH: Add external data management system

See merge request !135

* specify the algo preceded by a dash such as -algo
  with algo=[sha sha1 sha224 sha256 sha384 sha512 md5]

* specify the path to a folder or a file
    - if file: create key file at dest_path (=path by default)
    - if folder: go through all sub-directories and create key files at
      dest_path (=path by default) based on sub-directory architecture

/!\ WARNING /!\ : Won't work has expected if a directory contains dot!
  -> Because we identify a file if it contains dot for now

See https://github.com/MayeulChassagnard/BashScripting/blob/master/bash/convertToKeyFile.sh


Signed-off-by: Mayeul Chassagnard <mayeul.chassagnard@kitware.com>

* Add data needed for the examples inside Sandbox
    except ETI & textures
* Remove condition on DATA_ROOT_PATH since the user doesn't have to specify it
* Rename DATA_ROOT_PATH to iMSTK_DATA_ROOT according to 267b7f72

The device tracker stays up-of-date at all frames and is fixed by
setting m_trackingDataUptoDate to false at the end of the frame

Download Data from Girder according to data key files contained in iMSTK/Data

This uses ExternalData.cmake (Requires CMake >= 2.8.11 release).

Add TEST: Add ExternalDataTest to verify downloaded files from Girder
* Be sure the data requiered for the test is not there (delete it)
* Add the imstk_add_data(${target} ${data_list}) function in CMakeList.txt
which calls ExternalData_expand_arguments().
* It downloads the data provided by the data_list (relative path from
iMSTK/Data)

Add DOC: Add documentation on ExternalData Management
* How to add data to iMSTK from Grider
* Update data
* Use data

Add geometry test 2017.01.27

Closes #116

See merge request !127

According to e80f6f5ee92f17412034331d5561abb534d889ee
Test now passing:
setgetWidth(): Don't allow to change width if <= 0
setgetNormal(): Add m_normal parameter to rely on it when setgetNormal
And update rendering delegate part for the Plane.

Tests failing:
setgetWidth() with a width <=0
setgetNormal(): the vector returned by getNormal() is slightly different
from the one sent. Indeed, the normal is computed by the difference between
the orientation and the UP_VECTOR. In order to fix the issue, a m_normal
parameter must be added in the imstkPlane class.
Don't forget to update the rendering part based on this new m_normal vector

Fix #116 (in addition to getVolume formula fixes in imsktCube:
0280cec7)

Test now passing:
getVolume(): fix cube volume formula
setgetWidth(): Don't allow to change width if <= 0

see 1b1b018dc8f61e6b1737ed0de90c1c328d471dba

Tests failing:
getVolume()
setgetWidth() with a width <=0

Add laparoscopic tool controller

See merge request !119

Also correct indentation in Pbd class.

Create a tool with two jaws and a shaft. The controller
use its DeviceTracker to update the three objects

* Rename TrackingController to DeviceTracker
* Have subclasses store a pointer to DeviceTracker instead
of inheriting it. This allows:
1. swapping the tracking controller at runtime
2. having multiple controllers control for the same scene object (eg: laparoscopic tool jaw)
* Add SceneObjectControllerBase to parent SceneObjectController
and other future object controllers
* Update tracking data only once per frame: if the same tracker
is used for multiple objects, it is updated only once per frame.
Each tracker is set to upToDate once the tracking data is updated
and offsets computed once at each frame. At the end of the frame
all the device trackers are set to be outOfDate.

Scene can be set as current in the simulation manager using the scene
pointer in addition to its name.

We know we have only 4 buttons for the Omni

Scene object controllers are now part of the scene. They are looped through
in the sceneManager to update the objects they contain.

This will allow extension to the case where multiple scene objects are
controlled by the same controller (eg: two-jawed laparoscopic tool).

COMP: Fix eigen checkout

Closes #119

See merge request !126

Eigen git tag which was currently used (e81ac4502ebbfde43a1e1761b36853d3ead47c33)
can not be checked out anymore as of Sunday, January 29 2017 for unknown
reasons, causing all builds on the dashboard to fail:

http://my.cdash.org/index.php?project=iMSTK&date=2017-01-29

error:
```
fatal: reference is not a tree: e81ac4502ebbfde43a1e1761b36853d3ead47c33
```

Add VTK rendering improvements

Closes #115

See merge request !121

DOC: Add CONTRIBUTING.md

See merge request !125

Ensure the surface mesh read will only have triangles and
no triangle strips or other cells.