Runtime logging. (#3821)

* Implement Printable for tuples.

* Add debugging function.

* Add debug 1.

* Implement  for everything.

* RuntimeDebug derive.

* Introduce RuntimeDebug.

* Add some dummy logging.

* Replace RuntimeDebug with Debug.

* Revert "Replace RuntimeDebug with Debug."

This reverts commit bc47070a8cb30241b2b590b2fa29fd195088162f.

* Working on Debug for all.

* Fix bounds.

* Add debug utils.

* Implement runtime logging.

* Add some docs and clean up.

* Clean up derives.

* Fix custom derive impl.

* Bump runtime.

* Fix long lines.

* Fix doc test.

* Use CARGO_CFG_STD.

* Revert "Use CARGO_CFG_STD."

This reverts commit ea429566de18ed0fa052571b359eb9826a64a9f4.

* Use parse_macro_input

* Update lockfile.

* Apply review suggestions.

* Remove stray re-export.

* Add no-std impl.

* Update lockfile.

substrate/srml/contracts/src/exec.rs

@@ -60,7 +60,7 @@ impl ExecReturnValue {
 /// VM-specific errors during execution (eg. division by 0, OOB access, failure to satisfy some
 /// precondition of a system call, etc.) or errors with the orchestration (eg. out-of-gas errors, a
 /// non-existent destination contract, etc.).
-#[cfg_attr(test, derive(Debug))]
+#[cfg_attr(test, derive(sr_primitives::RuntimeDebug))]
 pub struct ExecError {
 	pub reason: &'static str,
 	/// This is an allocated buffer that may be reused. The buffer must be cleared explicitly
@@ -231,7 +231,8 @@ impl<T: Trait> Token<T> for ExecFeeToken {
 	}
 }
 
-#[cfg_attr(any(feature = "std", test), derive(Debug, PartialEq, Eq, Clone))]
+#[cfg_attr(any(feature = "std", test), derive(PartialEq, Eq, Clone))]
+#[derive(sr_primitives::RuntimeDebug)]
 pub enum DeferredAction<T: Trait> {
 	DepositEvent {
 		/// A list of topics this event will be deposited with.