The latest court appeal by a man who strangled his girlfriend in their Bayonne home, stuffed her body in a suitcase and left it on the Henry Hudson Parkway in the Bronx has been rejected. The state appellate court, in an 8-page decision released Wednesday, denied Shawn Southerland’s request for a new trial after his two previous bids for post conviction relief had been rejected. Southerland, who represented himself in the 2009 trial related to the 2007 murder of Christine Neely, also was unsuccessful in having his case heard by the state Supreme Court. Southerland’s main point of contention in…