Bpipe Version 0.9.9.4

Summary

This is a quick update that bundles a few new features with some critical fixes to 0.9.9.3 based on feedback after it was released.

Fix issue #217
Add bpipe stats command to show runtimes of stages
Support config of concurrency limit in bpipe.config, via concurrency=\<n>
- Support for embedding config inside pipeline scripts via 'config' statement
- Fix command status sometimes incorrect after stop preallocated
- Fix pool commands in WAITING status not recognised as active
- Fix trailing output from commands sometimes missing when output appears very fast at point where command terminates