Cleanup most of playlists.

Callback table handling left for later.
Switch to PyList_SET_ITEM as we always operate on new lists
Init search type to NULL
Use "O" in PyObject_CallFunction

Seems "N" does not have the behaviour I thought it did. Correct way to use this
is to allow the call to increase the refcount. self->ob_refcnt has been verfied
to be unchanged before and after the PyObject_CallFunction call.
Cleanup warnings from clang.