Add Utility Function for Collision detection
Handle DeformableRep external{Force|Stiffness|Damping} only when they exist.

When the number of degrees of freedom is big (500 to 1000), these vector and matrices are big enough that zeroing them and adding them up can take time.
So it makes sense to skip that step if none is present.
Renamed README to README.md

Since the README is markdown, rename it to README.md, so Assembla and
github can format it.
Make Shape::getType const

Shape::getType should be a const member function, this change makes it
one.
Add space in Accessible error message.

Just add a missing space after a '.' and before the next word in an
error message.
Fix formatting of doxygen style comments
Fix cpplint warnings
Fix registration for osgtext representation
Improve error reporting for some serialization features
Merge branch 'fix/rename-readme' into 'master'

Renamed README to README.md

+1: Julien Lenoir, Gughan Sathyaseelan, Harald Scheirich

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1309583
RigidRep: Add check to access external force/stiffness/damping
Fix typo euler -> Euler
Merge branch 'fix/cpplint_doxygen' into 'master'

Fix cpplint/doxygen warnings

+1: Harald Scheirich, Gughan Sathyaseelan, Paul Novotny

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1317503
Merge branch 'feature/collided-with' into 'master'

Utility function to check collision between two representations

+1: Gughan Sathyaseelan, Julien Lenoir, Ryan Beasley

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1291253
Merge branch 'fix/shape-get-type' into 'master'

Make Shape::getType const

+1: Harald Scheirich, Julien Lenoir, Gughan Sathyaseelan

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1313823
Merge branch 'fix/serialization-reporting' into 'master'

Slight improvements to error reporting in serialization

+1: Gughan Sathyaseelan, Julien Lenoir, Wesley Turner

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1317993
Merge branch 'fix/text-serialization' into 'master'

Fix registration in osgtextrepresentation

+1: Gughan Sathyaseelan, Julien Lenoir, Paul Novotny

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1317983
Merge branch 'feature/checkDeformableExternalForce' into 'master'

Handle DeformableRep::externalForce/Stiffness/Damping only when present.

+1: Wesley Turner, Paul Novotny

Merged-on: https://www.assembla.com/code/OpenSurgSim/git/merge_requests/1299373