ExampleStapling, add IdentityPoseDevice fallback
ExampleStapling, add deformable wound

- Adds PLY for the tetrahedron fem
- Adds PLY for the surface triangle mesh
- Loads the models and displays them
- Adds conversion from type produced by the ply reader delegate,
SurgSim::DataStructures::TriangleMesh, to the type used in graphics for
displaying meshes, SurgSim::Graphics::Mesh.
- Adds helper function for setting the physical parameters of the fem.
The parameters are required for valid initialization.
Physics unit tests, refactor out EXPECT_NEAR_EIGEN

- Refactored out testing macro for comparing eigen matrices for general
use.
Physics unit tests, refactor zero initialization of MlcpPhysicsProblem

- Refactored out zero initialization of MlcpPhysicsProblem from the unit
tests into a static constructing function in MlcpPhysicsProblem.
Bilateral3d Constraints, initial commit

- Implements bilateral constraints for fixed, rigid, and fem3d physics
representation types.
- Adds unit tests for each.
MlcpProblem, add Zeroing functions

- setZero is marked virtual
- destructor is marked virtual
Fix bug in rigid bilateral 3d constraint, use rotational dof

- Updated derivation to justify modifications
- Updated unit tests
Update fem3d bilateral 3d unit test, add extra test

- Adds extra test to verify the (coordinate != 0) portions of code work
correctly.
Minor bug fix in mass-spring bug fix in unit test

- Reserve 2 constraints to match the stated intention of the unit test.
Bilateral 3d constraints, various changes

- Replace helper function for counting non-zero items with idomatic call
for Eigen.
- Update documentation for fem3d bilateral 3d constraints.
- Add extra documentation for bilateral 3d constraints about their
purpose.
- Remove "explicit" from Constructors with no paramaters.
Fix problem with accessible type test

RigidTransform2x can't be serialized the way we are currently doing it
Took them out of the test
Bilateral 3d constraints, minor documentation update
Fix bug in rigid bilateral 3d, update derivation for H

- Computation with H involves only matrix multiplication, not a special
case with cross products in the solver.
Merge branch 'master' into feature/staple-example-load-fem

Conflicts:
	Examples/ExampleStapling/main.cpp
Add copy constructor to Graphics::Mesh
Stapler example, refactor mesh loader to use copy constructor
Fix bug in ply loader

- Desired allocation is is 1 + (the number of elements), not 1 char
larger than the number of elements.
Stapler example, use single ply file for fem tet and surface

- Rename ply file to use underscores rather than camelCase for
  consistency.
Stapler example, translate stapler out of arm
Stapler example, remove graphical collision representation