AbstractTransformer: Add some API for saving and restoring position information.
Fix #1227
Issue #1227: Enable the test and improve its coverage.
Issue #1227: Fix the optimized transformation of for (when iterating a range op).
Issue #1227: Add tests for the optimized transformation of for (when iterating a range op).
Update .src for tests now that Integral has gained a divides() method.
Update .src because print()'s parameter name was changed.