rt: fix jemalloc android cross-compile for mac
Cleanup src/librustc/back
syntax::diagnostics: Color the ^~~~ in green for better visibility

Fixes #7164.
extra: Add a testcase for #7256.
Avoid unnecessary scratch datums for by-copy function arguments

Currently, by-copy function arguments are always stored into a scratch
datum, which serves two purposes.  First, it is required to be able to
have a temporary cleanup, in case that the call fails before the callee
actually takes ownership of the value. Second, if the argument is to be
passed by reference, the copy is required, so that the function doesn't
get a reference to the original value.

But in case that the datum does not need a drop glue call and it is
passed by value, there's no need to perform the extra copy.
librustc: Don't allow enum struct variants to shadow structs.
Add test for duplicate definitions of structs and enum struct variants.
More 0.7 release notes
Show defaults in rustdoc usage message
fix text of tutorials
Update AUTHORS.txt
Minor doc updates to reflect #[deriving(Zero)], and small release notes adjustments.

The `extra::fileinput` module landed just after 0.6 was released, and there are many
more derivable traits.
Usable instructions for generating docs from source
vec: remove each_const

An Iterator implementation can be made for &const [T] if it turns out
to be necessary for some use case.
vec: remove eachi

replaced by the `enumerate` method from std::iterator
vec: rm old_iter implementations, except BaseIter

The removed test for issue #2611 is well covered by the `std::iterator`
module itself.

This adds the `count` method to `IteratorUtil` to replace `EqIter`.
vec: replace `position` with `iter().position_`
replace vec::find with the IteratorUtil method
auto merge of #7263 : thestinger/rust/iterator, r=graydon
auto merge of #7200 : yichoi/rust/fix_je_mac_cross, r=brson

while cross-compiling, ar in cross toolchains are required. 
linux is not sensitive so could not see errors.