Fix typo in comment.
- Added rolling friction to SphereOnSphereContact.
- Switched the contact frame to the Ancestor frame because that turned out to be more efficient.
- Precalculated all position and velocity quantities I could identify.
- Added unilateral sphere-sphere contact and modified RigidContact1's "Pencil" example to use it.
- Removed unnecessary data members in SpherePlaneContact (duplicated what is stored in the underlying constraint).
- Added some missing argument validity checks.
Added default geometry for two-point spring element (an orange rubber band line).
Added rubber band lines to RigidContact1 animation, and tweaked Pencil example.
Pencil example tweak.
- Reworked Constraint::Rod to use the distance constraint formulation from Constraint::SphereOnSphereContact. This replaced a "distance squared" constraint for Rod that had poor scaling and didn't play well with other contact constraints.
- Added new methods to Constraint::Rod to make it consistent with newer constraints and usable as a basis for a unilateral "rope" constraint (not implemented yet). Can now modify the end point locations and required length in State.
- Added lots of missing documentation for Rod.
- Doxygen improvements to SphereOnSphereContact.
- Fix regression test that failed due to change to Constraint::Rod. This test was too sensitive to minor changes in the assembled configuration due to the different perr condition (from distance^2 to distance).
- Added a comment to RodImpl.
Added unilateral Rope constraint based on the revised bilateral Rod constraint equations.
Fixes #139.

If using gcc or Clang and using C++11, then we fill in the OVERRIDE_11
and FINAL_11 macros with `override`, and `final`.

Note that the way I check if we're using C++11 is not completely
legitimate. The internet suggests doing feature-by-feature checks, since
most compiliers who say they are C++11 compliant are not necessarily
fully C++11 compliant. For the current C++11 features we use, there is
no issue.
Merge pull request #140 from chrisdembia/cpp11features

Fixes #139.
Update .travis.yml

Trying to debug a test failure that is only occurring on Travis.
The new equations for Contraint::Rod mean it is harder to assemble since the old equations squared the position error. That caused some small changes in TestObservedPointFitter that made some of its tests fail, though only when compiled with clang. These small changes appear to make it more robust.
Merge branch 'master' of https://github.com/simbody/simbody
Update .travis.yml

Removed now-unneeded hack.
Fix small typo (usin -> using).
Merge pull request #142 from chrisdembia/patch-1

Fix small typo (usin -> using).
Change SimTK_NICETYPENAME_LITERAL macro to open and close the SimTK:: namespace so that C++11 won't complain about a template specialization occuring outside the namespace where the original template was defined.

Note: this will no longer work properly if expanded inside the SimTK namespace!
Merge pull request #143 from simbody/fix_SimTK_NICETYPENAME_LITERAL

Change SimTK_NICETYPENAME_LITERAL macro to use SimTK namespace
Finish windows and mac instructions.

* Cleaned up some of the links.
* Created a more structured installation instructions section.