Minimaps

[Marlamin]

Bring back minimap browser, this time it has to be fully clientside which has some additional challenges as tiles can't be pre-cut.

Current idea is to do a wow.export-like implementation of loading BLPs onto a canvas. Not using leaflet, so things such as the ADT grid and game coordinate information will have to be re-implemented from the ground up. Also needs to show minimaps that only have names but aren't referenced by the WDT file.

Also, allow exporting entire minimap as PNG (might not be doable in browsers).