Hundreds of Donald Trump supporters have gathered in a festive atmosphere at the Waukesha County Expo Center for his appearance at a rally tonight. The program was scheduled to start at 6 p.m. and introductory speakers were expected to include Wisconsin Gov. Scott Walker, former Wisconsin Gov. Tommy Thompson and Milwaukee County Sheriff David Clarke, a source told me. The public address system inside the expo center dome was playing high volume classic rock – mostly the Rolling Stones and Elton…