Fews-3di

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- Added the functionality to provide a cold state file.
Place next to original state file with the name:
3di-cold-state-id.txt.

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- Added new rainfall modules, constant, csv and radar rain.

- Processing results into fews is now optional.

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- Checks for crashed status and queue's model.

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- Using a "streaming" download of large files to prevent partial downloads.

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- Added more resilience to local network errors. The loop that waits for
results to be ready checks the state every 30 seconds and is thus the most
vulnerable to wifi issues, a flaky VPN and local network hickups. We now
detect such a ``socket.gaierror`` there and simply try again in 30 seconds.

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- A minor bugfix in the result files which are downloaded after the simulation