Add travis-ci setup file.
Get travis-ci working.
Choose compilers for travis-ci.
Add library dependencies to travis.
Add library dependencies to travis.
Add library dependencies to travis.
Add library dependencies to travis.
Add library dependencies to travis.
Reduce travis dependencies for travis.
Reduce travis dependencies for travis.
Reduce travis dependencies for travis.
Don't build examples for travis testing.
Is apt-get update necessary?
Yes, apt-get update is necessary, for now.
Delete whitespace.
Do not build visualizer in travis.
Merge pull request #25 from chrisdembia/travistesting

Automated testing using Travis-CI. 
Chris is helping me get the Travis build going ...
Merge branch 'master' of https://github.com/simbody/simbody
Add missing try-catch around main code.

Signed-off-by: Michael Sherman <msherman@stanford.edu>
Fix bug in SimbodyMatterSubsystem::multiplyByMInv() reported by Chris Dembia as issue #29 on GitHub: it was unnecessarily requiring the state to have been realized through Dynamics stage; it actually only depends on Position-level quantities. This made the method unsuited for use during a force calculation, where only position and velocity information is available.