Fix the following cases:
  - tuples
  - 'L' and 'K'
  - 'D'
  - 's#' and 'z#'
  - 'et#'
  - 'w' and its variants

Simplify type comparison by stripping off "const" and signedness modifiers from the front of types

Avoid having to manually write a rule for each number of variable arguments to PyArg_ParseTuple etc by capturing each argument in turn (with lists of prior and subsequent expressions).  The downside is that the rule is invoked once per argument at each callsite, with knowledge of only one type, rather than invoking it once per callsite with knowledge of all arguments.

Thanks to Julia Lawall and Nicolas Palix