std::str: Use CharIterator in NormalizationIterator

Just to simplify and not have the iteration logic repeated in multiple places.
std::str: Fix bug in .slice_chars()

`s.slice_chars(a, b)` did not allow the case where `a == s.len()`, this
is a bug I introduced last time I touched the method; add a test for
this case.
extra::dlist: Fix bug in Eq::ne
Add missing space
doc/rust.md: Missing in keyword on keyword list.
auto merge of #8877 : bouk/rust/master, r=sanxiyn

Ran into a missing space in the stdlib source
auto merge of #8858 : blake2-ppc/rust/small-bugs, r=alexcrichton

Fix a bug in `s.slice_chars(a, b)` that did not accept `a == s.len()`.

Fix a bug in `!=` defined for DList.

Also simplify NormalizationIterator to use the CharIterator directly instead of mimicing the iteration itself.
auto merge of #8878 : toqueteos/rust/patch-1, r=sanxiyn

As promised on #8876.
Revert "Teach the makefile to use multiple src-base's"

This reverts commit 43f851d2cb3976655078f032dc1a8cb88f1c8deb.
Revert "Teach compiletest to use multiple --src-base's"

This reverts commit 8a07f5708196dd72ec030018c2a215a4dd823b2e.
Revert "src/test/bench: restructure"

This reverts commit 14cdc26e8a7794e437946f46df5769362b42acdf.
auto merge of #8886 : cmr/rust/test-restructure, r=cmr
fix various warnings
rustc: capitalize types in rscope.rs
std: Add a fixme for when we add Trait::<for T>::static_method()