ENH: relocate sortedOrder from ListOps.H to List.H

- commonly used, only depends on routines defined in UList
  (don't need the rest of ListOps for it).

ENH: implement boolList::operator() const

- allows use as a predicate functor, as per bitSet and labelHashSet

GIT: combine SubList, UList into List directory (intertwined concepts)

STYLE: default initialize DynamicList instead of with size 0