residualize names into procedures. re-implement srfi-61. module naming foo.

residualize names into procedures. re-implement srfi-61. module naming foo.

* module/ice-9/boot-9.scm (cond): Implement srfi-61; most of the code is
  from the SRFI itself. Yuk.
  (%print-module, make-modules-in, %app, (%app modules))
  (module-name): Syncase needs to get at the names of modules, even at
  anonymous modules. So lazily assign gensyms as module names. Name %app
  as (%app), but since (%app modules) is at the top of the module
  hierarchy, name it ().

* module/ice-9/psyntax.scm: When building tree-il, try to name lambdas in
  definitions and in lets.
  (let, letrec): Give more specific errors in a couple of cases.

* module/ice-9/psyntax-pp.scm: Regenerated.

* test-suite/tests/syntax.test: More work. Many exceptions have different
  messages than they used to, many more generic; we can roll this back to
  be faithful to the original strings, but it doesn't seem necessary to
  me.