Fix wrong error msg in creating fcl meshes
Add abi_check.sh for api checking
ABI check on Travis-CI
Fix incorrect command for abi check in .travis.yml
Install abi-compliance-checker on Travis-CI
Fix typo in abi_check.sh
Merge pull request #223 from dartsim/is_reactive

Rename isImpulseReponsible() to isReactive()
BallJointConstraint works, but the simulation becomes unstable for two-body cases
merged
restored SPD in bipedStand app
Fix bugs of WeldJointConstraint in two bodies case
Fix bugs of WeldJointConstraint for two bodies in one skeleton (closed chain)
Not allow arbitrary relative transformation for weld joint constraint
- The relative transformation between two bodies of weld joint constraint is initially set to their relative transformation when the weld joint constraint is made.
- This is necessary to prevent instability of dynamics from the initial constraint error due to arbitrary relative transformation
Remove undeclared definitions
- The declarations were removed by previous commit
Test rigidLoop with WeldJointConstraint instead of BallJointConstraint
- It will be replaced BallJointConstraint back once BallJointConstraint is stabilized
Merge pull request #224 from dartsim/fix_weld_joint_constraint

Fix weld joint constraint
Rename *Vector -> *s of API for equations of motion
Change virtual functions of Skeletons to non-virtual
- Skeleton was inherited by SoftSkeleton for soft body dynamics but they are merged to one class to Skeleton so we don't need virtual functions anymore.
Fix minor bug in SkelParser
master -> abi_check