Fix sample program to compile in modern rust
Moved experimental compiler flags to -Z (#4740)
Added a few missing 'pub's
add a BaseIter implementation for PriorityQueue
core: Remove transitional code
rm each method from the Map trait

the map types should implement BaseIter instead
implement BaseIter for TreeMap
make Option's map and map_default use a lifetime
implement BaseIter for SmallIntMap
add a ReverseIter trait
implement ReverseIter for TreeMap and TreeSet
implement ReverseIter for SmallIntMap
implement BaseIter for LinearMap
auto merge of #4834 : veddan/rust/zflags, r=graydon

Converted --static, --gc, --jit, -g and --xg to -Z flags.
fix map tests
Fixed #1531
auto merge of #4835 : thestinger/rust/iterator, r=graydon

This adds a `BaseIter` impl to `PriorityQueue`, `TreeMap`, `LinearMap` and `SmallIntMap`, and introduces a `ReverseIter` trait + implementations for `TreeMap`, `TreeSet` and `SmallIntMap`.
core: Remove structural records from the rest of core, except pipes

That will, sadly, require one more snapshot.
auto merge of #4839 : catamorphism/rust/rm-structural-records, r=catamorphism
auto merge of #4843 : ILyoan/rust/i1531, r=catamorphism

Fix for #1531