Some struct visibility fixes

src/libextra/url.rs

@@ -21,7 +21,7 @@ use std::to_bytes;
 use std::uint;
 
 #[deriving(Clone, Eq)]
-struct Url {
+pub struct Url {
     scheme: ~str,
     user: Option<UserInfo>,
     host: ~str,
@@ -32,7 +32,7 @@ struct Url {
 }
 
 #[deriving(Clone, Eq)]
-struct UserInfo {
+pub struct UserInfo {
     user: ~str,
     pass: Option<~str>
 }

src/libstd/rt/io/mem.rs

@@ -128,7 +128,7 @@ impl Decorator<~[u8]> for MemReader {
 
 
 /// Writes to a fixed-size byte slice
-struct BufWriter<'self> {
+pub struct BufWriter<'self> {
     buf: &'self mut [u8],
     pos: uint
 }
@@ -156,7 +156,7 @@ impl<'self> Seek for BufWriter<'self> {
 
 
 /// Reads from a fixed-size byte slice
-struct BufReader<'self> {
+pub struct BufReader<'self> {
     buf: &'self [u8],
     pos: uint
 }