container: inline contains_key default method
iterator: add a `range_inclusive` function

Closes #6242
rm obsolete integer to_str{,_radix} free functions
rm obsolete float to_str_radix free functions
vec: add `shrink_to_fit`

Closes #4960
option: derive Clone/DeepClone for the iterator
iterator: add a method for reversing a container

this works on any container with a mutable double-ended iterator
enable tests for the container tutorial
Deleted fun_treemap

@thestinger and I talked about this in IRC. There are a couple of use
cases for a persistent map, but they aren't common enough to justify
inclusion in libextra and vary enough that they would require multiple
implementations anyways.

In any case, fun_treemap in its current state is basically useless.
Fix typo in test/bench/noise.rs. Closes #8574.
auto merge of #8582 : thestinger/rust/container, r=thestinger

5f3a637 r=huonw
934a5eb r=thestinger
0f6e90a r=cmr