Add Pretty instances for Shape, ExtShape, and ExtShapeDim.
Add Pretty instances for Shape, ExtShape, and ExtShapeDim.

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