message: Improve verbosity of panic messages in CsMat
diff: @@ -1077,14 +1077,26 @@ where
  let outer = self.outer_dims();
  if self.indptr.len() != outer + 1 {
  - panic!("Indptr length does not match dimension");
  + panic!(
  + "Indptr length does not match dimension: {} != {}",
  + self.indptr.len(),
  + outer + 1
  + );
  }
  if self.indices.len() != self.data.len() {
  - panic!("Indices and data lengths do not match");
  + panic!(
  + "Indices and data lengths do not match: {} != {}",
  + self.indices.len(),
  + self.data.len()
  + );
  }
  let nnz = self.indices.len();
  if nnz != self.nnz() {
  - panic!("Indices length and inpdtr's nnz do not match");
  + panic!(
  + "Indices length and inpdtr's nnz do not match: {} != {}",
  + nnz,
  + self.nnz()
  + );
  }
  if let Some(&max_indptr) = self.indptr.iter().max() {
  if max_indptr.index() > nnz {
  