[WF4] Simplified accessing variables from an activity's arguments

-Simplified handling of variable from ancestor Activities that are in
scope. Noted some potential bugs with the previous system that didn't
show through due to happy coincidence.
-Removed ability of ActivityEnvironment, a LocationReferenceEnvironment
subclass, to check the variables in scope and much of its implementation
of LRE methods until it's clearer what they should do.
-There is also a simple logging system just for use on an ad hoc basis
during development. Whats logged is liable to change, wont work so well
with multiple contributors.