Switch core language array type syntax to the one Fritz proposed in #179.
Switch core language array type syntax to the one Fritz proposed in #179.

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