PHILADELPHIA — Christian DeJohn returned from a National Guard tour in Bosnia only to fight his own war with academics at Temple University who he says have held up his master's thesis because of political conflicts in the classroom.To some conservatives, the case represents a national trend by some liberal professors to infringe on conservative students' right to free speech at public colleges and universities. The debate has reached more than a dozen state legislatures, which dole out the taxpayer funds to those schools, but so far there's been more talk than action. Legislation modeled after an "academic bill of...