add Iterator implementations for Option
option: remove redundant old_iter impls
fix windows build
rustc: Remove task type defs from trans
Add a finally impl for `extern "Rust" fn()`
Ignore the test_package_request_version test for now
Codegen: Combine two PointerCasts into one

Shaves off a percent or so from the LLVM passes for librustc.
fix the ptr::set_memory docstring
fix the docstring for copy_nonoverlapping_memory
auto merge of #7055 : thestinger/rust/iterator, r=catamorphism

This was a lot more painful than just changing `x.each` to `x.iter().advance` . I ran into my old friend #5898 and had to add underscores to some method names as a temporary workaround.

The borrow checker also had other ideas because rvalues aren't handled very well yet so temporary variables had to be added. However, storing the temporary in a variable led to dynamic `@mut` failures, so those had to be wrapped in blocks except where the scope ends immediately.

Anyway, the ugliness will be fixed as the compiler issues are fixed and this change will amount to `for x.each |x|` becoming `for x.iter |x|` and making all the iterator adaptors available.

I dropped the run-pass tests for `old_iter` because there's not much point in fixing a module that's on the way out in the next week or so.
auto merge of #7056 : alexcrichton/rust/issue-4727, r=catamorphism

Closes #4727
std: convert {vec,str}::to_owned to methods.
std: replace str::append with a method
std: convert str::repeat to a method.
std: convert str::{*shift,pop}* to methods.
std: unify the str -> [u8] functions as 3 methods: .as_bytes() and .as_bytes_with_null[_consume]().

The first acts on &str and is not nul-terminated, the last two act on strings
that are always null terminated (&'static str, ~str and @str).
std: add a test for HashMap::find_equiv.
std: remove substr & str::count_*, methodise char_len, implement slice_chars.

The confusing mixture of byte index and character count meant that every
use of .substr was incorrect; replaced by slice_chars which only uses
character indices. The old behaviour of `.substr(start, n)` can be emulated
via `.slice_from(start).slice_chars(0, n)`.
std: methodise str::capacity
std: convert str::replace to a method.