changed matrix fvar typedefs
added more autodiff tests for block
added more autodiff tests to col and cols
modified test naming for agrad/fwd
added more autodiff tests for columsn_dot_prod, columns_dot_self,crossprod,cumulative_sum,det
added autodiff tests to diag_matrix, diag_post_mult,diag_pre_mult
added dot_prod and diag autodiff tests
added autodiff tests for dot_self, elt_div,elt_mult,exp,inv,log_det
added autodiff tests for log,max
added autodiff tests for all mdivides
fixed typos