In a blockbuster move that analysts have speculated about in recent years, Milwaukee-based Journal Communications Inc. will split into two companies with the Milwaukee Journal Sentinel joining a new publishing company with E.W. Scripps Co. newspapers and Journal Broadcast Group's radio and television stations merging with Scripps broadcast stations. The transaction announced Wednesday night will mean Journal's decades-old Milwaukee broadcast properties WTMJ-TV (Channel 4), WTMJ-AM (620) and WLWK…