dirty changes - stabilization hacks
first experiments with RK4
made the multiDof-singleDof disctinction a bit cleaner
a bit of rk4 clean-up
RK4 for floating systems too
minor naming chamge
dirty commit: experimenting with the 6DoF grabbing/p2p constraint
tighter packing in btMultiBodySolverConstraint
dirty commit: starting to unify btMultiBoydConstraint::fillMultiBodyConstraint..(..)
fixed a jacobian sizing bug (m_jacSizeBoth)
unified btMultiBodyConstrained::fillMultiBodyConstraint..(...) mtds + cleaned some of the earlier dirty changes (6DoF grabbing constraint stuff mainly)
minor clean-up
fixed the multibody jitter issue + several friction-related fixes
fixed a btMultiBody ctor bug
preparing for stabilization investigation: useRK4 is now a btMultiBody flag (not world's), reenabled global velocities (as a flag-controlled option), made the test application easier to handle for multiple multibodiez and added a max coordinate multibody (created from btMultiBody)
minor: replaced convenience lambda functions