Exception handling stuff.
Merge branch 'master' of github.com:rjpower/falcon
Acquire a reference to a function when caching.

Avoid terrible, terrible problems with reference counted object reuse.
Minor fixes:

  By default, disable to_string on objects when dumping instruction log.
  Calling PyObject_Repr/ToStr appears to affect the reference counts of
  things causing behavior to diverge from the unlogged case.

  More work on exception handling.