Fix unwinding on OS X 10.9.

OS X 10.9's linker has a bug that results in it failing to preserve
DWARF unwind information when passed the -no_compact_unwind flag.
This flag is passed on OS X because the unwind information for
__morestack cannot be represented by the compact unwind format.

We can work around this problem by using a more targeted approach
to disabling compact unwind information. The OS X linker looks for
a particular pattern in the DWARF unwind information and will not
attempt to convert the unwind information to the compact format.
The pattern in question is the return address register being saved
twice to the same location.

Fixes #6849.
Minor grammatical fixes and removed section on 'rust' tool
Don't Make str field private
Making fields in std and extra : private  #4386
Removed Unnecessary comments and white spaces  #4386
Removed unnecessary comments and white spaces as suggested
Removed the unnecesary comments
Removed the file src/libstd/unstable/extfmt.r
auto merge of #10013 : bdash/rust/mavericks-unwinding, r=alexcrichton

OS X 10.9's linker has a bug that results in it failing to preserve
DWARF unwind information when passed the -no_compact_unwind flag.
This flag is passed on OS X because the unwind information for
__morestack cannot be represented by the compact unwind format.

We can work around this problem by using a more targeted approach
to disabling compact unwind information. The OS X linker looks for
a particular pattern in the DWARF unwind information and will not
attempt to convert the unwind information to the compact format.
The pattern in question is the return address register being saved
twice to the same location.

Fixes #6849.
Making ai_next field public
auto merge of #9969 : reedlepee123/rust/priv_fields, r=bstrie
auto merge of #10020 : mletterle/rust/documentation-fixes, r=thestinger

I'm planning on doing more updates, but the section in the tutorial stood out at me since the 'rust' tool no longer exists, this should probably be removed to lessen confusion.
libsyntax/librustc: Allow specifying mut on by-value self.
libsyntax/librustc: Allow specifying mut on ~self.
Add tests for uniq & by-value self in mut slot.
Update the manual.