Fix: missing call to 'dump_gen_code'.
Lazy evaluation: first draft
DAG building, use static descendant computation instead of ancestors during DAG building
Deactviate construction and output of the delayed computation DAG.

Unused ATM and very slow.
demo airfoil, avoid recreating new 'rms' global, replace with delayed reset of 'rms'
Make Const setter lazy
Make Mat lazy.
Remove Access from op2 interface
Fix unit test to account for Const lazy setter
Save Const._defs at ParLoop creation for execution-time
Make reshape strict in delayed Const setter.
Make reshape strict in Global.setter
Fix license text, docstrings, and comments.
Fix: missing global statements
refactor Dummy and LazyComputation classes