Fix implicit leaks of imports throughout libraries

Also touch up use of 'pub' and move some tests around so the tested functions
don't have to be 'pub'

src/libsyntax/ext/log_syntax.rs

@@ -14,6 +14,7 @@ use ext::base::*;
 use ext::base;
 use print;
 
+use core::io;
 use core::io::WriterUtil;
 use core::option;