Enable btMultiBodyJointLimitConstraint, seems to be working for the prismatic joint
Fix case sensitive issue, thanks to Martin Felis
Fix crash/bug in btMultiBodyConstraint computation

git-svn-id: http://bullet.googlecode.com/svn/trunk@2678 08e121b0-ae19-0410-a57b-3be3395fd4fd
Add a virtual createConstraintRows method, to easier experiment with different kinds of btMultiBodyConstraint


git-svn-id: http://bullet.googlecode.com/svn/trunk@2679 08e121b0-ae19-0410-a57b-3be3395fd4fd
add a btFixedConstraint with toggle between btGeneric6DofConsraint and btFixedConstraint in VoronoiFractureDemo

git-svn-id: http://bullet.googlecode.com/svn/trunk@2680 08e121b0-ae19-0410-a57b-3be3395fd4fd
change btMultiBody to allow removal/changing of links
(still not easy to modify the link structure of a btMultiBody -> You have to manually re-link parents, copying links around etc)

git-svn-id: http://bullet.googlecode.com/svn/trunk@2681 08e121b0-ae19-0410-a57b-3be3395fd4fd