* Wrap expression inside EvalToTemp in copy_using_evaluators() if we
assume aliasing for that expression (that is, for products)
* Remove temporary kludge of evaluating expression to temporary in
AllAtOnce traversal
* Implement EvalToTemp expression object
* Make product EvalAtOnce in cases OuterProduct, GemmProduct and
GemvProduct
* Ensure that product evaluators are nested inside EvalToTemp
evaluator
* As temporary kludge, evaluate expression to temporary in AllAtOnce
traversal and pass expression operator to evalTo()
- Add evaluator_traits with HasEvalTo flag, which is true if evaluator
has evalTo() function.
- Add AllAtOnce traversal, which calls evalTo() in evaluator.
- If source evaluator in copy_using_evaluator has HasEvalTo set, then
use AllAtOnce traversal.
* Rename the old copy_using_evaluators to noalias_copy_using_evaluators.
* Write a new copy_using_evaluators which strips NoAlias expression, if present,
and calls noalias_copy_using_evaluators; in future, it will also take care of
aliasing in products.
* Add expression() getter to NoAlias.
