Improve labeling of highest category for threshold scale

[wahlatlas]

suppose you are using a threshold scale for 5 colors like this

       scale: 'threshold',
       domain: [400, 500, 600, 700],

then the upper most category should be labeld either
> 700
or
700 and above
but not both

see here

[floledermann]

This should have been fixed by the recent refactoring of legend generation. Built mapmap.js checked in in master, release forthcoming.

Also watch out for examples collection detailing legend configuration coming soon.