removed debug code.
added getAABB method.
added
modified getAABB method.
update to calc physcs.
added
removed unuse code.
added a new method.
to use solve constraint.
optimize a little.
removed a comment out.
added condition to pair type.
bug fixed that increase pair number.
commented out a var.
implemented mass 0 solver.
update
Merge branch 'create-world' into gh-pages