Missing translation fields

[kobaj]

The following need to be set (to what I think is most reasonable)

general.user from the shift sign up page: https://d2dlvh7py5vl2n.cloudfront.net/shift-entries?action=create&shift_id=1&angeltype_id=1

Should probably just translate to "User"

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From: https://engelsystem.furcon.org/login

event.buildup.start -> "Pre-event setup"
event.starts -> "Event start"
event.ends -> "Event end"
event.teardown.ends -> "Teardown"

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From: https://d2dlvh7py5vl2n.cloudfront.net/shifts?action=view&shift_id=2

shifts.start -> "Shift start"
shifts.end -> "Shift end"