Make typechecker properly check transposes with a negative direction.
Make typechecker properly check transposes with a negative direction.

diku-dk/futhark,HIPERFIT/futhark,ihc/futhark,mrakgr/futhark,CulpaBS/wbBach,HIPERFIT/futhark,mrakgr/futhark,diku-dk/futhark,diku-dk/futhark,diku-dk/futhark,mrakgr/futhark,ihc/futhark,diku-dk/futhark,HIPERFIT/futhark,ihc/futhark