Fix a bloody stupid bug in BDD quick simplification.
Make sure that the EC driver's bubble log works properly in
multi-process mode.
Update a helper script a bit.
Make it possible to configure the simplifiers off.
Add some more tests which more directly explore the effects of
complicated HB graphs and complicated aliasing behaviour.
Make the split-process stuff optional.
Sanify makefiles a little.
Track memory high water mark as well as total time.
Get rid of a bad assertion.
Fix the availability map calculations.  An expression is available at
a node if it's available at any of its message predecessors or if it's
available at all of its control-flow predecessors.  That means that
stuff which is received on a message is only available if it's
available on every CF predecessor.
Make the makefiles behave themselves with filenames which contain
special characters.
Slightly better complex_alias test.