issue #4118: refactor physics update
issue #4118: add PhysicsBody::setResting()
issue #4118:  fix bit mask bug
issue #4118:  add _isDamping to PhysicsBody and fix bugs
issue #4118: add physics contact test.
reset project.pbxproj
issue #4118:  rename set/getElasticity to set/getRestitution
issue #4118:  change PhysicsBody::updateDamping() to protected.
Merge pull request #5460 from boyu0/iss4118_physical_performance_improve

issue #4118: Physical performance improve.