Fix signature and add string_reader to ioivec.

Author: graydon

src/lib/ioivec.rs

@@ -220,10 +220,14 @@ obj byte_buf_reader(byte_buf bbuf) {
     fn tell() -> uint { ret bbuf.pos; }
 }
 
-fn new_byte_buf_reader(&u8[] buf) -> byte_buf_reader {
+fn new_byte_buf_reader(&u8[] buf) -> buf_reader {
     ret byte_buf_reader(@rec(buf=buf, mutable pos=0u));
 }
 
+fn string_reader(&str s) -> reader {
+    ret new_reader(new_byte_buf_reader(str::bytes_ivec(s)));
+}
+
 
 // Writing
 tag fileflag { append; create; truncate; none; }