Brief overview of PR changes/additions

Add an outline colour chooser to map label creation window in mapper. Update createMapLabel Lua function to reflect this as well. Adds three optional arguments to the end of createMapLabel( ..., outlineRed, outlineGreen, outlineBlue), default to the same colour as foreground if not specified.

Also, chosen colours weren't being saved from one dialog to the next forcing unnecessary typing to replicate a colour scheme when creating multiple labels, so fix this and allow chosen colours to also save across Mudlet restarts as well.

Motivation for adding to Mudlet

Better user experience, more map design options, prettier maps.

Other info (issues closed, discussion etc)

• The outline width is only 1 pixel, but as fonts get smaller this starts to become increasingly larger compared to the width of the small font. Zoomed in fonts (or larger than 16 on my display) typically look better.
• Based on this work I think it would be fairly trivial to add drop shadows, mirroring and other text effects.

Zoomed in;

closes #2861
/claim #2861