* beginnings to testclient implementation for more complete wallet API testing
* rework TestWalletClient to be message-based proxy
* test fix
* wallet tests now exercising the API directly as much as possible, capable of instantiating multiple wallets
* test in place to run both file and db wallets
* ensure all wallet api functions lock wallet as needed. Split up transaction creation from posting to chain
* Added sizeshift to proof of work and encoding as VLQ
* Fix some loose ends to get things to compile
* Rename sizehift to min_sizeshift
* Pipeline checks for PoW Cuckoo Cycle size shift and adjustment
factor before difficulty comparison.
* Working delta+VLQ encoding of u64 PoW, unfortunately still a
little larger than u32, at least for Cuckoo30.
* Changed binary encoding of proof of work to a sequence of exact
compact bit representation of each nonce. Somewhat simpler,
shorter and matches the data to be hashed.
* Few fixes based on @tromp feedback:
* Max nonce is 2^(N-1)
* Need a separate constant for reference sizeshift
* Cuckoo implementation now conserves sizeshift. Test providing a
block at higher sizeshift.
* Last small overflow protection
* First pass at restructuring the keychain crate and introducing a Keychain trait
* Parameterized everything that had to. Stuff compiles.
* More stuff compiles, fix most tests
* Big merge, pushing down opening the keychain forced adding factory methods on trait
* Test fixes for pool and servers crate
* move http calls out from libwallet internal
* rustfmt
* start to think about wallet communication traits
* rustfmt
* start of factoring out wallet client trait
* rustfmt
* move node_url trait fn into walletclient
* rustfmt
* comms factored out (with exception of wallet restore)
* rustfmt
* fix test
* rustfmt
* further test fix
