NAME
	solidify_mapping - order a mapping into arrays of equal indexes

SYNTAX
	mapping solidify_mapping(mapping m);

DESCRIPTION
	This efun returns a mapping of this form:
	([
	  index1 : ({ all data in m that had index1 }),
	  index2 : ({ all data in m that had index2 }),
	  ....
	])

	It replaces the old unique_array.

EXAMPLE
	solidify_mapping(([1:3,1:5,10:6,4:5,1:3,4:5,10:11]));
	would return:
	([
	  1:({3,5,3}),
	  4:({5,5}),
	  10:({6,11}),
	])

SEE ALSO
	map_array, mkmapping