fix std::cmp docstring
update FuzzyEq to explicit self
add a FuzzyEq method that accepts an epsilon value
Fix two code examples in main rust tutorial.

1. The section on trait definitions of static methods should include
   a trait with a static method in the generated document.

2. The section on trait inheritance had a expression that appears
   nonsensical ("let mycircle = @mycircle") in the generated document.
   The text would be clearer (IMO) if we continued with the running
   example of CircleStruct.
Fixed two examples of erroneous code so their errors match expectation.

1. In the first case, the previous code was failing during type inference
   due to mismatched structure.  Fix is to use the X structure at both
   points in the code.

2. In the second case, a naive transcription that subsitutes *nothing*
   in for the omitted statements signified by "..." will actually
   compile without an error.  Furthermore, any pure code could also be
   substituted for the ellipsis and the code would compile (as the
   text already states).  So to make the example more illustrative, it
   would be better to include an impure callback, which makes the
   potential for aliasing immediately obvious to the reader.
Formatting cleanup.

I had put a line break in to try to stress the binding of mycircle,
but generated document looks cleaner without newline.
Add expected failure annotation on "fixed" example to placate 'make check'.
implement fuzzy_eq with fuzzy_eq_eps
Merge pull request #4664 from thestinger/fuzzy

FuzzyEq improvements
testsuite: Xfail file that I added by mistake
Fix licenseck to allow 2012-2013 as the year range
fix FuzzyEq
libsyntax: De-export a lot of libsyntax. rs=deëxporting
Merge pull request #4676 from thestinger/fuzzy

fix FuzzyEq
libsyntax: De-export libsyntax. rs=deexporting
librustc: De-export driver. rs=deexport
librustc: De-export back, lib, and util. rs=deexporting
librustc: De-export front, borrowck, and typeck/check. rs=deexporting
librustc: De-export typeck. rs=deexporting
librustc: De-export metadata. rs=deexporting