Add FIXED_SEGMENT_LENGTH, MIN_SEGMENT_LENGTH and MAX_SEGMENT_LENGTH to
SIMEVENTS SEGMENT events. The lengths are stored on RimWellEventSegment
(new AddSegmentEvent arguments, 0 = not set) and applied to the segment
interval when the timeline is applied. Invalid combinations (fixed with
min/max, min > max, non-positive values) are reported as parse errors.
Rename RimWellEventTubing to RimWellEventSegment (keyword WellEventSegment),
EventType::TUBING to SEGMENT, and the scripting method AddTubingEvent to
AddSegmentEvent (Python: add_segment_event). Update the project tree label,
schedule comments, Python helpers, examples, tests and docs.