The main tealet (the one calling in to python) must be suspended and the top
level tasklet evaluation loop run in a worker, because soft switching may
have the main tasklet run in an arbitrary tealet when it exits.  It then
needs to switch back to the 'main' tealet.  The only way to do this is
to have the 'main' tealet in a known state.

In the old system, it was possible to switch back to a known state of the
main stack, creating a duplicate on the fly.  Tealets are more strict because
a tealet are more like threads:  each can only run a function, not
extend back from its invocation point.

This is safe and recommended, structs have their own namespace and their
names don't clash with typedefs.

tealet to return to.  This also removes then need to tweak it
in the test_outside function.

re-implement stackless.uncollectable.

The platf/ files are still present in the repo.

Fix cleanup to work properly.

…e original

one.

We now just call a callback for the initial stub.  There is no need
to mess with cframes and such stuff.

This is a lot of legacy, it should all work through tealets now.

soft-swiching of the main tasklet, and the consequence of the main
tasklet being executed on a different stack when it exits, it is much
simpler to simply force hard switching for the main tasklet.  This
means that the main tasklet always runs on the stack provided by
the caller into the python library, including whatever stack
exception handlers they provided.
This removes the need to have the main tealet suspended while stackless
runs.

Unittest test_thread are broken here and need fixing.