Convert all UK spelling to US (#2138)

* all the ise

* forgot a misspelling

* a few more replacements

* bump impl

* rollback and fixes

* bump impl again

* Add aliases for RPC

* Update on_demand.rs

substrate/core/sr-version/src/lib.rs

@@ -91,7 +91,7 @@ pub struct RuntimeVersion {
 	/// serves only as an indication that the code is different; as long as the other two versions
 	/// are the same then while the actual code may be different, it is nonetheless required to
 	/// do the same thing.
-	/// Non-consensus-breaking optimisations are about the only changes that could be made which
+	/// Non-consensus-breaking optimizations are about the only changes that could be made which
 	/// would result in only the `impl_version` changing.
 	pub impl_version: u32,