Unify the mutable iterators too. Switch the ListInsertion trait to use
method .insert_next() and .peek_next() for list mutation. .insert_next()
inserts an element into the list that will not appear in iteration, of
course; so the length of the iteration can not change during iteration.
Did not properly allow runs from the `other` list to be merged in. The
test case was using a wrong expected value.
Edited docs for merge so they explain more clearly what it does.
Also make sure insert_ordered is marked pub.
An iterator that allows mutating the list is very useful but needs care
to not be unsound. ListIteration exposes only insert_before (used for
insert_ordered) and peek_next so far.
This is an owned sendable linked list which allows insertion and
deletion at both ends, with fast traversal through iteration, and fast
append/prepend.
It is indended to replace the previous managed DList with exposed list
nodes. It does not match it feature by feature, but DList could grow
more methods if needed.
the `test/run-pass/class-trait-bounded-param.rs` test was xfailed and
written in an ancient dialect of Rust so I've just removed it
this also removes `to_vec` from DList because it's provided by
`std::iter::to_vec`
an Iterator implementation is added for OptVec but some transitional
internal iterator methods are still left
