OpenGl_View now caches bounding boxes per Z-layer (instead of bounding box of entire scene in Graphic3d_CView).
Redundant invalidation of cached scene bounding box is now avoided in case
when new presentation attributes are assigned to the graphic structure.
Add a new methods ConsiderZoomPersistenceObjects() and considerZoomPersistenceObjects() in the Graphic3d_CView, OpenGl_View and OpenGl_Layer classes.
Call ConsiderZoomPersistenceObjects() in the V3d_View::FitMinMax method.
std::numeric_limits<T>::lowest() fix
