Merge smaller branches to simplify review process

Closes:

- rust-lang#1758
- rust-lang#1757
- rust-lang#1756

src/fn/closures.md

@@ -26,7 +26,7 @@ fn main() {
     // TODO: uncomment the line above and see the compiler error. The compiler
     // suggests that we define a closure instead.
 
-    // Closures are anonymous, here we are binding them to references
+    // Closures are anonymous, here we are binding them to references.
     // Annotation is identical to function annotation but is optional
     // as are the `{}` wrapping the body. These nameless functions
     // are assigned to appropriately named variables.

src/std/hash/alt_key_types.md

@@ -3,7 +3,7 @@
 Any type that implements the `Eq` and `Hash` traits can be a key in `HashMap`. 
 This includes:
 
-* `bool` (though not very useful since there is only two possible keys)
+* `bool` (though not very useful since there are only two possible keys)
 * `int`, `uint`, and all variations thereof
 * `String` and `&str` (protip: you can have a `HashMap` keyed by `String`
 and call `.get()` with an `&str`)