Rewrite of documentation for recip.process_to_q

- Exposed the frame_mode variable as an input parameter to
  recip.process_to_q
- Added new tests to make sure that bad entries for frame_mode
  actually fail and that good entries do not raise an exception
yes you are right detector_size : tuple order is (num_columns, num_rows). However, here we only need to multiplication of  [num_imges*num_rows*num_columns] therefore, either num_imges*num_rows*num_columns or num_imges*num_columns*num_rows will give the same answer