add Graphemes iterator; tidy unicode exports

- Graphemes and GraphemeIndices structs implement iterators over
  grapheme clusters analogous to the Chars and CharOffsets for chars in
  a string. Iterator and DoubleEndedIterator are available for both.

- tidied up the exports for libunicode. crate root exports are now moved
  into more appropriate module locations:
  - UnicodeStrSlice, Words, Graphemes, GraphemeIndices are in str module
  - UnicodeChar exported from char instead of crate root
  - canonical_combining_class is exported from str rather than crate root

Since libunicode's exports have changed, programs that previously relied
on the old export locations will need to change their `use` statements
to reflect the new ones. See above for more information on where the new
exports live.

closes #7043
[breaking-change]

4 files changed, 5 insertions, 6 deletions

diff --git a/src/libstd/io/mod.rs b/src/libstd/io/mod.rs
index 6ac092fd8c6..c1c918ad3b3 100644
--- a/src/libstd/io/mod.rs
+++ b/src/libstd/io/mod.rs
@@ -237,7 +237,7 @@ use str::{Str, StrSlice};
 use str;
 use string::String;
 use uint;
-use unicode::UnicodeChar;
+use unicode::char::UnicodeChar;
 use vec::Vec;
 
 // Reexports
diff --git a/src/libstd/path/windows.rs b/src/libstd/path/windows.rs
index 88ae0d4837e..02d9dc44489 100644
--- a/src/libstd/path/windows.rs
+++ b/src/libstd/path/windows.rs
@@ -24,7 +24,7 @@ use option::{Option, Some, None};
 use slice::{Vector, ImmutableVector};
 use str::{CharSplits, Str, StrAllocating, StrVector, StrSlice};
 use string::String;
-use unicode::UnicodeChar;
+use unicode::char::UnicodeChar;
 use vec::Vec;
 
 use super::{contains_nul, BytesContainer, GenericPath, GenericPathUnsafe};
diff --git a/src/libstd/prelude.rs b/src/libstd/prelude.rs
index a20ac112ac5..eee494c7bc0 100644
--- a/src/libstd/prelude.rs
+++ b/src/libstd/prelude.rs
@@ -59,7 +59,7 @@
 #[doc(no_inline)] pub use ascii::{Ascii, AsciiCast, OwnedAsciiCast, AsciiStr};
 #[doc(no_inline)] pub use ascii::IntoBytes;
 #[doc(no_inline)] pub use c_str::ToCStr;
-#[doc(no_inline)] pub use char::Char;
+#[doc(no_inline)] pub use char::{Char, UnicodeChar};
 #[doc(no_inline)] pub use clone::Clone;
 #[doc(no_inline)] pub use cmp::{PartialEq, PartialOrd, Eq, Ord};
 #[doc(no_inline)] pub use cmp::{Ordering, Less, Equal, Greater, Equiv};
@@ -77,7 +77,7 @@
 #[doc(no_inline)] pub use ptr::RawPtr;
 #[doc(no_inline)] pub use io::{Buffer, Writer, Reader, Seek};
 #[doc(no_inline)] pub use str::{Str, StrVector, StrSlice, OwnedStr};
-#[doc(no_inline)] pub use str::{IntoMaybeOwned, StrAllocating};
+#[doc(no_inline)] pub use str::{IntoMaybeOwned, StrAllocating, UnicodeStrSlice};
 #[doc(no_inline)] pub use to_str::{ToString, IntoStr};
 #[doc(no_inline)] pub use tuple::{Tuple1, Tuple2, Tuple3, Tuple4};
 #[doc(no_inline)] pub use tuple::{Tuple5, Tuple6, Tuple7, Tuple8};
@@ -89,7 +89,6 @@
 #[doc(no_inline)] pub use slice::{Vector, VectorVector};
 #[doc(no_inline)] pub use slice::MutableVectorAllocating;
 #[doc(no_inline)] pub use string::String;
-#[doc(no_inline)] pub use unicode::{UnicodeChar, UnicodeStrSlice};
 #[doc(no_inline)] pub use vec::Vec;
 
 // Reexported runtime types
diff --git a/src/libstd/rt/backtrace.rs b/src/libstd/rt/backtrace.rs
index 09922b5ad76..1594e3ba0a2 100644
--- a/src/libstd/rt/backtrace.rs
+++ b/src/libstd/rt/backtrace.rs
@@ -21,7 +21,7 @@ use os;
 use result::{Ok, Err};
 use str::StrSlice;
 use sync::atomics;
-use unicode::UnicodeChar;
+use unicode::char::UnicodeChar;
 
 pub use self::imp::write;