Clean up sr-io (#3609)

* Move trait `Printable` into `sr-primitives`

* Cleanup runtime io trie_root interfaces

* Remove last generic bits from sr-io interface

* Fix srml-sudo after master merge

* Fix benchmarks

* Runtime bump

substrate/srml/democracy/src/lib.rs

@@ -562,7 +562,7 @@ decl_module! {
 
 		fn on_initialize(n: T::BlockNumber) {
 			if let Err(e) = Self::end_block(n) {
-				runtime_io::print(e);
+				sr_primitives::print(e);
 			}
 		}