Create dumps on signals

[akruis]

I need support for the following use case: a Python program hangs (i.e. a server process in accept(2)). An admin kills the process. Upon termination the process writes a dump for post mortem analysis.

Currently the exepthook provided by pyheapdump ignores exceptions not derived from Exception. As a consequence it ignores a SIGINT (ctrl-C). And any other exception simply kills the python process.