Pack the component argNames descriptions.

* timestream/manipulate/pipecomponents.py (argNames): Reduce the number of lines
per argName comment to a minimum.
min() should have at least 1 element

* timestream/parse/__init__.py (ts_guess_manifest_v1): Make sure we don't call
min when intervals is empty.
Image reading: Skimage -> cv2 -> None

* timestream/__init__.py (read, pixels): Make sure we try all possibilities
before we default to None.
Fix Return statements on components

* timestream/manipulate/pipecomponents.py (ResultFeatureWRiter_csv,
ResultingFeatureWriter_ndarray, PopulateMetaIds): They return a list containing
an image.