Towards removing McSAF collections.

A couple of straggers:

* FlowSet is implemented by VFFlowset. TODO refactor VFFlowset to use
Java collections instead.
* One analysis in Tamer uses HashMapFlowSet. TODO fix this
Replace VFFlowset with Map<String, VFDatum>.

Fairly big clean up, moving towards removing McSAF collections
(here FlowSet, AbstractFlowSet, etc.).
Refactor HandleFlowset away from HashMapFlowSet.

This is the last use of HashMapFlowSet, and so of
AbstractFlowSet, and FlowSet.

(incidentally, this handle propagation analysis looks a little
sketchy, and doesn't appear to be used anywhere.)
Fix remaining references to VFFlowset in AST2XML.
Merge branch 'no-more-mcsaf' into develop