Update dependencies and bigint api (#5685)

* update to latest bigint

* bump elastic array and deps

* fix rlp tests

* also update all smallvec deps

* fix doc test

* reduce parking in attempt to fix CI bug

* fix from/into electum bug

* remove duplicate imports

util/rlp/benches/rlp.rs

@@ -15,7 +15,7 @@
 #![feature(test)]
 
 extern crate test;
-extern crate ethcore_bigint as bigint;
+extern crate bigint;
 extern crate rlp;
 
 use test::Bencher;