Among other things, passing fixed parameters can improve the accuracy
of temp shape inference, so that fallback can occur less often.

The motivation for this is to remove the temp_shape_fallback warnings
when constructing sumpy kernels.

cacheable before creating the cache key.

get included in dependency calculcations.

Add a save and reload test that uses base_storage.

array prefixes as they are aded to the set.

Closes #25 on gitlab
Depends on inducer/pytools!2 on gitlab

type. Now, the argument to a reduction can be either a scalar or a
tuple.

either a tuple, reduction, or a substitution invocation).

Also, rewrite the reduction mapping code to rely on recursive calls
map_tuple(). This cleans up a lot of reduction mapping code
substantially.

dependencies, and also to treat loops more carefully.

* Dependencies are now tracked based on a list of active potential
  sources, and the active set is narrowed by filtering through
  readers/writers
* Stricter handling of dependencies within loops by not assuming
  that loops are nonempty
* Changes the barrier insertion algorithm to act in two stages: first,
  barriers are recursively inserted into loops, then they are inserted
  at the outermost level. This is mostly meant to simplify the code.
* See also #18 on gitlab

check that the index returned is a minimum, rather than the exact value from numpy (in case of duplicate min/maxs)