* add block number * add ext_current_block * add ext_current_block test * Update srml/contracts/src/wasm/mod.rs Co-Authored-By: Sergei Pepyakin <s.pepyakin@gmail.com> * Update srml/contracts/src/wasm/mod.rs Co-Authored-By: Sergei Pepyakin <s.pepyakin@gmail.com> * change valid comment * use BlockNumberOf<T> * Update srml/contracts/src/exec.rs Co-Authored-By: André Silva <andre.beat@gmail.com> * return types copy, not reference * version up spec_version and impl_version * change method name current_block -> block_number * Update srml/contracts/src/exec.rs Co-Authored-By: Sergei Pepyakin <s.pepyakin@gmail.com>