ENH: support List sub-slice searching, use std::find()

- support UList shallowCopy with pointer/size
  (eg, for slicing into or from span)

ENH: add SubList::reset() functionality

- allows modification of a SubList after construction.
  Previously a SubList had an immutable location after construction
  and there was no way to shift or change its location.

BUG: missed special handling for DynamicList<char>::readList (fixes #2974)

- equivalent to List<char>::readList, in which the stream is
  temporarily toggled from ASCII to BINARY when reading in a List of
  char data.
  This specialization was missed when DynamicList<T>::readList() was
  fully implemented.