Undocumented predicates

The following predicates are exported, but not or incorrectly documented.

 alias(Arg1, Arg2)

 dimension_symbol(Arg1, Arg2)

 kind(Arg1)

 quantity_character(Arg1, Arg2)

 quantity_formula(Arg1, Arg2)

 quantity_parent(Arg1, Arg2)

 prefix(Arg1, Arg2, Arg3)

 absolute_point_origin(Arg1, Arg2)

 no_space_before_unit_symbol(Arg1)

 prefix(Arg1, Arg2, Arg3)

 relative_point_origin(Arg1, Arg2)

 unit_kind(Arg1, Arg2)

 unit_symbol(Arg1, Arg2)

 unit_symbol_formula(Arg1, Arg2, Arg3)

 qeval(Arg1)