* 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
* remove context object from aggsig and transaction libs
* fix to aggsig, and remove unnecessary warnings
* put tx_fee function into libwallet::transaction
* Error cleanup, and creating libwallet error type
* remove some unwraps
* checker bug
* ensure transaction tests checks sender's wallet
* Beginning to rework aggsig library workflow
* more refactoring of transaction api
* whoever does round 1 first creates offset
* slate finalisation now context-free, so anyone can do it
* remove concept of transaction phase
* remove slate phase enum
* update actual send/receive code with new transaction lib workflow
* beginning to refactor keychain into wallet lib
* rustfmt
* more refactor of aggsig lib, simplify aggsig context manager, hold instance statically for now
* clean some warnings
* clean some warnings
* fix wallet send test a bit
* fix core tests, move wallet dependent tests into integration tests
* repair chain tests
* refactor/fix pool tests
* fix wallet tests, moved from keychain
* add wallet tests