ppmpf tuple / sequence items always enclosed during folding.

The change affects a series of macros already implemented and makes certain
that each item passed to the binary function macro that is used during
folding is enclosed by balanced parentheses, therefore covering the case
of processing a sequence made out of tuples as items being folded. Thus,
the "dereferencing" macro has no longer meaning as an argument in the
recursive macros making up the basis for the fold construct.
Easy transformation of ppmpf item lists into their reverses.
Introducing right folds for ppmpf collections (tuples, sequences).

By introducing a tuple / sequence reversal function macro, ppmpf can now
provide for right folds as well. Finished transition to balanced parentheses
return from fold algorithms and applied fixes to headers using them. From now
on, ppmpf tuples / sequences are to be referred to as "collections". Notice
that folding over a collection will always return a parenthesis enclosed
preprocessor token.