Read The RestMatthew Vaughn has decided not to direct the sequel to20th Century Fox‘s hit spinoff X-Men: First Class. Ready for the next shocker? Atop the studio’s replacement short list is Bryan Singer, who launched the X-Men feature franchise with the first two superb films and who has been a guiding influence in this spinoff by writing the treatment and producing. If this works out, Singer and Vaughn would essentially be switching roles. Vaughn, who wrote the treatment for the sequel for X-Men: Days Of Future Past that was scripted by Simon Kinberg, would step back to produce the film with Kinberg…