add prim._const, ParserInterface.makeLiteralReporter

prim._const is not currently employed by the compiler, but may be
useful in some scenarios, such as for users of the controlling API.
(See TestArgumentInjection, coming soon in a separate commit, is a
sample use.)

ExpressionParser.makeLiteralReporter now supports _const and is
accessible through nvm.ParserInterface.  (Ditto on the sample use.)
make Evaluator support passing in CompilerFlags

I need this in TestArgumentInjection.  but it's just generally
a good thing.  (I'd do the same thing in nvm.Workspace, but I'm
reluctant to make life harder for people using our APIs from
Java.)
add demo code for passing arguments to job manager jobs

TestArgumentInjection is a demo written in test form.
it shows how to work around issue #413