[stable] Backports (#8133)

* updater: apply exponential backoff after download failure (#8059)

* updater: apply exponential backoff after download failure

* updater: reset backoff on new release

* Limit incoming connections.  (#8060)

* Limit ingress connections
* Optimized handshakes logging

* Max code size on Kovan (#8067)

* Enable code size limit on kovan

* Fix formatting.

* add some dos protection (#8084)

* more dos protection (#8104)

* Const time comparison (#8113)

* Use `subtle::slices_equal` for constant time comparison.

Also update the existing version of subtle in `ethcrypto` from
0.1 to 0.5

* Test specifically for InvalidPassword error.

* revert removing blooms (#8066)

* Revert "fix traces, removed bloomchain crate, closes #7228, closes #7167"

This reverts commit 1bf62038678295e5586f02a38a0c5aab9a9efe62.

* Revert "fixed broken logs (#7934)"

This reverts commit f8a2e53f3e.

* fixed broken logs

* bring back old lock order

* remove migration v13

* revert CURRENT_VERSION to 12 in migration.rs

* Fix compilation.

* Check one step deeper if we're on release track branches

* add missing pr

* Fix blooms?

* Fix tests compiilation.

* Fix size.

json/src/spec/params.rs

@@ -113,6 +113,9 @@ pub struct Params {
 	/// See main EthashParams docs.
 	#[serde(rename="maxCodeSize")]
 	pub max_code_size: Option<Uint>,
+	/// See main EthashParams docs.
+	#[serde(rename="maxCodeSizeTransition")]
+	pub max_code_size_transition: Option<Uint>,
 	/// Transaction permission contract address.
 	#[serde(rename="transactionPermissionContract")]
 	pub transaction_permission_contract: Option<Address>,