ADT.OrderedMapping: Improve docs.
ADT.OrderedMapping: Fix duplicate entries, optimise and add substract.
Merge remote-tracking branch 'origin/master' into new_utf8
ADT: Protect even more lfuns.
Merge remote-tracking branch 'origin/8.1' into gobject-introspection
ADT.OrderedMapping: Had forgotten the ->=() method and changed all key (index) arguments to mixed.
New class ADT.OrderedMapping.
This class emulates a mapping but will keep the order of the indices as they were added.