Eternity_common.cfg

Probably fixed probable I/O race condition when loading images.
Fixed Visual mode stuttering due to floating point precision degradation when running the editor for several days without restarting (internal timer is now reset when saving the map or creating a new one).
Fixed, Nodes Viewer, cosmetic: Nodes Viewer window position was reset after pressing the "Rebuild Nodes" button.
Added Eternity Game configurations by printz.
Updated ZDoom_ACS.cfg (CheckClass).
Updated ZDoom ACC (CheckClass).