Fix various doc tests

[cpeterso]

The manual's link attribute example code did not compile! For new users that copy and paste example code (like I did), this is pretty frustrating. The master and 0.5 branches have the same doc bug. Since this is a small fix for a frustrating problem, you might consider cherry picking this fix to those branches.

OpenSSL's SHA1() function takes a size_t, according the Darwin and Linux header files. The FFI tutorial was inconsistently using both uint and libc::c_uint.

Enable lint warnings for doc tests. I thought this would be a good way to ensure that the docs' example code uses the latest coding style. Is the big, multi-line """ ... """ string too ugly?

For lint warnings that many doc tests fail (e.g. deprecated_self, non_camel_case_types, structural_records), I just enabled them as #[ warn(...) ] as a reminder to possibly forbid them in the future.

Also fix some typos and remove some semicolons (!!) from the doc test generator Python script.

[catamorphism]

Great, thanks!

[catamorphism]

Sorry, I had to revert the FFI tutorial patch because our Linux bot doesn't (I guess) have the right library installed -- http://buildbot.rust-lang.org/builders/incoming-full-linux/builds/342/steps/test/logs/stdio

[cpeterso]

oops, sorry! make check worked on my Mac. <:)

[catamorphism]

No worries! Maybe it's our bot that's wrong and it should have that library? Then again, maybe we don't want to require all users to have it just to build the docs.