ENH: simplify/extend IOobjectList code with templated predicates

- replace explicit use of word, wordRe, wordRes, wordHashSet as filters
  with a MatchPredicate, since they all satisfy the requirements for
  use a predicate. This change reduces code duplication, allows other
  matcher types (eg, keyType) as well as lambda functions.

- add special treatment for a 'const char*' parameter
  for lookupClass() and the now-deprecated single item lookup() method
  to promote these parameters to 'word'.