

Tracing version of the old optimiser. 
Much of this is automatically generated
by some very simple rules in add-rules.str
(using Stratego-Front). Then manual changes are
needed to fix things. add-rules is subject to constant
change (as part of another project) so it is expected
that the process will become more automated over time.

trace-strats. contains most of the tracing infrasture 
called during recording and replay of the tracing.

