Change Shl<T, T> for Int to Shl<uint, T>
Small fixes for tutorial.

5.2 Simplify example to remove hidden #[deriving(Show)].
    Add example for constructing the enums.

8   Reference later sections describing rc, gc and send.
    Fix for #15293.

13  Simplify BananaMania example to remove hidden code.

17  Gave an example using the derived Rand trait.

Removed references to removed 'extra' crate.
str: Add better tests for string slice's Chars iterator

Test using for ch s.chars() { black_box(ch) } to have a test that should
force the iterator to run its full decoding computations.
core::str: Implement Chars iterator using slice::Items

Re-use the vector iterator to implement the chars iterator.

The iterator uses our guarantee that the string contains valid UTF-8,
but its only unsafe code is transmuting the decoded u32 into char.
Add more tests for str Chars iterator

Test iterating (decoding) every codepoint.
sync: Ensure try_send() wakes up receivers

This branch of try_send() just forgot to wake up any receiver waiting for data.

Closes #15761
Fill in documentation for HashSet.

Example how to use the set with a custom type. Fill in examples for the missing methods.
sync: Fail with init semaphore count < 0

Semaphores are not currently designed to handle this case correctly, leading to
very strange behavior. Semaphores as written are intended to count *resources*
and it's not possible to have a negative number of resources.

This alters the behavior and documentation to note that the task will be failed
if the initial count is 0.

Closes #15758
Remove examples from trait implementations. Unhide imports.
Include Strings guide with the others.

Three small changes:

1. Re-organize headers in the Strings guide so they show up correctly.
2. build the strings guide with the other docs
3. include the strings guide in the list of guides
Remove outdated unreachable check from `call_visit_glue`

`call_visit_glue` is only ever called from trans_intrinsic, and the
block won't be unreachable there. Also, the comment doesn't make sense
anymore. When the code was introduced in 38fee9526a the function was
also responsible for the cleanup glue, which is no longer the case.

While we're at it, also fixed the debug message to output the right
function name.
Correct plural of arguments in format_args!
Assign more diagnostic codes
Special case for 0 arguments given in format!
librustc: Emit enum variant constructor at callsite instead of via a call to a function.
librustc: Emit tuple struct constructor at callsite instead of via a call to a function.
librustc: Only emit constructor functions as necessary.
librustc: Set enum discriminant only after field translation.
Ignore one test.
Remove the unneeded final parameter from call_visit_glue

call_visit_glue() is only ever called with None as its last argument, so
we can remove it as well.