* signer/clef: make use of json-rpc notification
* signer: tidy up output of OnApprovedTx
* accounts/external, signer: implement remote signing of text, make accounts_sign take hexdata
* clef: added basic testscript
* signer, external, api: add clique signing test to debug rpc, fix clique signing in clef
* signer: fix clique interoperability between geth and clef
* clef: rename networkid switch to chainid
* clef: enable chainid flag
* clef, signer: minor changes from review
* clef: more tests for signer
