FILTERMAP

Order	Name	Type	Desc
1	original	map	The map to be filtered
2	filterkey	const	The name of the map item to be searched for
3	filtervalue	const	The value of the map item to allow

Places an map on the stack.

This function filters the map (original). Any item that does not contain the specified filterkey and filtervalue will be removed.

For example, if you had the following map in your stack…

 [ { "name": "alpha",
     "colour": "orange",
     "style": "plain" },
    { "name": "beta",
      "colour":"blue",
      "style":"exotic"} ]

…then the command 'colour' 'blue' FILTERMAP will remove 'alpha' from your map, leaving only 'beta'.