function cloneArray(arr, index) {
    var a = [];
    var len = arr.length;
    for (var i = index || 0; i < len; i++) {
        a[i] = arr[i];
    }
    return a;
}
Compares the paths passed in with the tree.  Any of the paths that are in
the tree will be stripped from the paths.

**Does not mutate** the incoming paths object.
**Proper subset** only matching.

@param {Array} paths - A list of paths (complex or simple) to strip the
intersection
@param {Object} tree -
@public