Make generic, removing dependency on node_runtime (#1)

* Extract error to file

* Update readme

* Extract Rpc to separate file

* Make Rpc generic over Runtime

* Editor config etc.

* rustfmt

* Remove node-runtime dependency, generic soup

* Move generic trait bounds to impl

* rustfmt

* Remove unused stuff

* Add test for balance transfer call

src/error.rs

@@ -0,0 +1,35 @@
+// Copyright 2018-2019 Parity Technologies (UK) Ltd.
+// This file is part of substrate-subxt.
+//
+// ink! is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// ink! is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with substrate-subxt.  If not, see <http://www.gnu.org/licenses/>.
+
+use jsonrpc_core_client::RpcError;
+use std::io::Error as IoError;
+use substrate_primitives::crypto::SecretStringError;
+
+#[derive(Debug, derive_more::From)]
+pub enum Error {
+	Io(IoError),
+	Rpc(RpcError),
+	SecretString(SecretStringError),
+	Other(String),
+}
+
+impl From<&str> for Error {
+	fn from(error: &str) -> Self {
+		Error::Other(error.into())
+	}
+}
+
+pub type Result<T> = std::result::Result<T, Error>;