Thread safe changes for Histogram classes
Reverse total to be mutable non-atomic since totalValid can be used as a lock
Put back total were it was in orig version
Put back total were it was in orig version
Move total out of #if and add comment about its safeness (Chris' suggestion)
Add std::memory_order_acquire; align code w/ noexpandtab option in vim
align code w/ noexpandtab option in vim
Fix the loads
Merge pull request #908 from vkuznet/ThreadSafe_PhysicsToolsObjects

Thread safety fixes -- PhysicsToolsObjects