Harry Potter fans dressed up and waited in line for hours outside the Uptown Theater Tuesday night. Photo by Andrew Helms. Written by DCist contributor Andrew Helms Forget vampires. Harry Potter and co. stormed back on the scene last night in Harry Potter and the Half-Blood Prince, to the delight of would-be teenage wizards and witches everywhere. DCist checked out the midnight premiere at the Uptown Theater in Cleveland Park, where Potter fans lined…