Bugfix/issue 1131 int locals not params

#### Summary:

Allow integer local variables to be treated as data rather than parameters, no matter where they show up.  This is not just ODE related.

#### Intended Effect:

Fix bug and provide intended behavior.

#### How to Verify:

Run the new example model, which is reproduced in the repo now from issue #1131 

The new behavior for the AST function at the heart of the problem now has a unit test in the AST tests.

#### Side Effects:

None.

#### Documentation:

Not user facing.  Now behaves as expected.

#### Reviewer Suggestions:

Daniel or Mitzi.