Fixed str::raw::push_byte

It was previously pushing the byte on top of the string's null
terminator. I added a test to make sure it doesn't break in the future.
fix warning still mentioning the `again` keyword
Implemented iterator for TrieMap

Closes #5506.
Remove debug printing.
Add extra::arena::Arena::new{, _with_size}.

Signed-off-by: OGINO Masanori <masanori.ogino@gmail.com>
auto merge of #8183 : omasanori/rust/migrate-new, r=sanxiyn

It seems that relatively new code uses `Foo::new()` instead of `Foo()` so I wrote a patch to migrate some structs to the former style.
Is it a right direction? If there are any guidelines not to use new()-style, could you add them to the [style guide](https://github.com/omasanori/rust/wiki/Note-style-guide)?
auto merge of #8289 : sfackler/rust/push_byte, r=erickt

It was previously pushing the byte on top of the string's null
terminator. I added a test to make sure it doesn't break in the future.
auto merge of #8292 : thestinger/rust/fix_loop_warning, r=brson
auto merge of #8293 : dim-an/rust/trie-iterator, r=thestinger

Closes #5506.