Trollflow

-------------------
- Update changelog. [Panu Lahtinen]
- Bump version: 0.5.2 → 0.6.0. [Panu Lahtinen]
- Merge pull request 2 from pytroll/develop. [Panu Lahtinen]

Add Python 3 support
- Merge pull request 1 from pytroll/feature-python3-support. [Panu
Lahtinen]

Python 3 compatibility
- Change print statements to functions, fix exceptions. [Panu Lahtinen]
- Remove mpop examples as there's no Python 3 support. [Panu Lahtinen]
- Use six to import queue, cast dict_items to tuple. [Panu Lahtinen]
- Delete potentially large internal variables to reduce memory use.
[Panu Lahtinen]

-------------------
- Update changelog. [Panu Lahtinen]
- Bump version: 0.5.1 → 0.5.2. [Panu Lahtinen]
- Rename to more descriptive filename. [Panu Lahtinen]
- Update example to match current package structures. [Panu Lahtinen]
- Update readme. [Panu Lahtinen]

-------------------
- Update changelog. [Panu Lahtinen]
- Bump version: 0.5.0 → 0.5.1. [Panu Lahtinen]
- Fix PyYAML case as dependency in setup.cfg. [Martin Raspaud]

-------------------
- Update changelog. [Panu Lahtinen]
- Bump version: 0.4.0 → 0.5.0. [Panu Lahtinen]
- Fix restarting crashed workers/daemons. [Panu Lahtinen]
- Catch ValueError. [Panu Lahtinen]
- Add "flush_queue" kwarg. [Panu Lahtinen]

When setting flush_queue=False, the queued items can be kept when
restarting worker

- If previous worker died, release its lock. [Panu Lahtinen]

NOTE: this need to be done so that all the downstream workers have
finished working so that there won't be synchronisation issues

- Clarify log message. [Panu Lahtinen]
- Remove exception handling for MemoryError. [Panu Lahtinen]

In this way the thread "watchdog" can restart the worker without losing
all the existing items in the queues

- Find dead workers only when not shutting down. [Panu Lahtinen]
- Use also old output queues so possibly existing data are kept. [Panu
Lahtinen]
- Recreate dead threads, reconnect queues and locks. [Panu Lahtinen]

-------------------
- Update changelog. [Panu Lahtinen]
- Bump version: 0.3.2 → 0.4.0. [Panu Lahtinen]
- Add optional forced garbage collection. [Panu Lahtinen]

-------------------
- Update changelog. [Panu Lahtinen]
- Bump version: 0.3.1 → 0.3.2. [Panu Lahtinen]
- Add missing import. [Panu Lahtinen]
- Use UTC timestamps in log files by default. [Panu Lahtinen]
- Catch MemoryError. [Panu Lahtinen]
- Fix finally/except misuse. [Panu Lahtinen]
- Make loop exit cleaner. [Panu Lahtinen]
- Catch all errors, not only KeyboardInterrupt. [Panu Lahtinen]
- Daemonize all worker threads. [Panu Lahtinen]