Change BEAM lights and sights to accept width instead of arc

[kwvanderlinde]

Identify the Bug or Feature request

Improves #4448

Description of the Change

Instead of an arc= parameter, BEAM lights and sights now take a width= parameter measured in map units (same as ranges).

Also includes clean up for SightType and fixed sight output in getInfo("campaign").

Possible Drawbacks

It's possible to make beams so wide they don't look like beams anymore.

Documentation Notes

BEAM lights can take width= parameter to set the thickness of the beam.

Release Notes

N/A

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This change is 

[bubblobill]

The code looks good to me, but I couldn't find a default value for width in the parsing (I just got out of bed so may have missed it). A default width should be thin enough to be useful but thick enough to be visible.
Something like this, fiddlethe value to produce a satisfactory result.

this.width = (width == 0) ? 0.2 : width;
this.arcAngle = (arcAngle == 0) ? 90 : arcAngle;

Aim for something like this

[kwvanderlinde]

@bubblobill Any default value or lower bound for width won't necessarily be meaningful for all maps as they can have wildly settings. So instead I changed the meaning of width=0 (or any tiny width) to mean a rectangle that's just about as thin as possible, something we can determine dynamically.