Added rechecking for docking during the night.
Use `is None` instead of `not`.

Same as strands-project/strands_executive#116
Merge pull request #13 from lucasb-eyer/patch-1

Use `is None` instead of `not`.
Merge pull request #12 from hawesie/hydro-devel

Added rechecking for docking during the night.
Checking for is not None explicitly. Sorry @lucab-eyer.
Merge pull request #14 from hawesie/hydro-devel

Checking for is not None explicitly. Sorry @lucab-eyer.
Merging in latest changes and changing end time to 23:59