Spelling fixes (#571)

* docs: fix spelling and whitespace errors

tokio-io/src/_tokio_codec/decoder.rs

@@ -1,3 +1,3 @@
-// For now, we need to keep the implmentation of Encoder in tokio_io.
+// For now, we need to keep the implementation of Encoder in tokio_io.
 
 pub use codec::Decoder;

tokio-io/src/_tokio_codec/encoder.rs

@@ -1,3 +1,3 @@
-// For now, we need to keep the implmentation of Encoder in tokio_io.
+// For now, we need to keep the implementation of Encoder in tokio_io.
 
 pub use codec::Encoder;

tokio-io/src/async_read.rs

@@ -52,7 +52,7 @@ pub trait AsyncRead: std_io::Read {
     /// `prepare_uninitialized_buffer`.
     ///
     /// This function isn't actually `unsafe` to call but `unsafe` to implement.
-    /// The implementor must ensure that either the whole `buf` has been zeroed
+    /// The implementer must ensure that either the whole `buf` has been zeroed
     /// or `read_buf()` overwrites the buffer without reading it and returns
     /// correct value.
     ///

tokio-io/src/async_write.rs

@@ -82,7 +82,7 @@ pub trait AsyncWrite: std_io::Write {
     /// appropriate. This method is the hook for such protocols to implement the
     /// graceful shutdown logic.
     ///
-    /// This `shutdown` method is required by implementors of the
+    /// This `shutdown` method is required by implementers of the
     /// `AsyncWrite` trait. Wrappers typically just want to proxy this call
     /// through to the wrapped type, and base types will typically implement
     /// shutdown logic here or just return `Ok(().into())`. Note that if you're

tokio-io/src/framed.rs

@@ -99,7 +99,7 @@ impl<T, U> Framed<T, U> {
     /// being worked with.
     pub fn into_parts(self) -> FramedParts<T> {
         let (inner, readbuf) = self.inner.into_parts();
-	    let (inner, writebuf) = inner.into_parts();
+        let (inner, writebuf) = inner.into_parts();
         FramedParts { inner: inner.0, readbuf: readbuf, writebuf: writebuf }
     }