add a place to keep track of the number of simulation steps where acceleration was close to gravity for a given Entity

libraries/entities/src/EntityItem.cpp

@@ -74,6 +74,7 @@ EntityItem::EntityItem(const EntityItemID& entityItemID) {
     _created = UNKNOWN_CREATED_TIME;
     _dirtyFlags = 0;
     _changedOnServer = 0;
+    _accelerationNearlyGravityCount = 0;
     _element = NULL;
     _simulatorIDChangedTime = 0;
     _shouldClaimSimulationOwnership = false;

libraries/entities/src/EntityItem.h

@@ -343,6 +343,7 @@ protected:
     glm::vec3 _velocity;
     glm::vec3 _gravity;
     glm::vec3 _acceleration;
+    quint8 _accelerationNearlyGravityCount;
     float _damping;
     float _lifetime;
     QString _script;