Backports for beta 2.2.5 (#10047)

* bump beta to 2.2.5

* Fix empty steps (#9939)

* Don't send empty step twice or empty step then block.

* Perform basic validation of locally sealed blocks.

* Don't include empty step twice.

* Strict empty steps validation (#10041)

* Add two failings tests for strict empty steps.

* Implement strict validation of empty steps.

* ethcore: enable constantinople on ethereum (#10031)

* ethcore: change blockreward to 2e18 for foundation after constantinople

* ethcore: delay diff bomb by 2e6 blocks for foundation after constantinople

* ethcore: enable eip-{145,1014,1052,1283} for foundation after constantinople

* Change test miner max memory to malloc reports. (#10024)

* Fix: test corpus_inaccessible panic (#10019)

If system uptime is less than the duration in the test, thread
will panic due to: 'overflow when subtracting duration from instant'.

Changed duration to 20 seconds to make it unlikely the test will
fail due to this condition.

Since no operations that carry a similar risk of panic occur outside
of the tests, it doesn't seem warranted to depend on an external crate
to fix this.

* Bump crossbeam. (#10048)

json/src/spec/authority_round.rs

@@ -68,6 +68,8 @@ pub struct AuthorityRoundParams {
 	/// Maximum number of accepted empty steps.
 	#[serde(rename="maximumEmptySteps")]
 	pub maximum_empty_steps: Option<Uint>,
+	/// Strict validation of empty steps transition block.
+	pub strict_empty_steps_transition: Option<Uint>,
 }
 
 /// Authority engine deserialization.