* make slate v0 the default for regular sends
* add block_header_version to slate
* update doc tests for latest grin version
* rustfmt
* HACF if HF height detected
* rustfmt
* add issue_invoice_tx command
* rustfmt
* add first pass at process_invoice command
* start of process_invoice fn
* rustfmt
* rename issue invoice and process invoice to invoice and pay
* add prompting and display information to pay invoice command
* rustfmt
* support invoice transactions in finalize command
* rustfmt
* move api deser types into separate types mod
* rustfmt
* missing types file
* make all exports from libwallet more explicit
* rustfmt
* add version check function to foreign api
* rustfmt
* change check_version return value to result, for consistency
* store receiver's output into the sender's database
* rustfmt
* payment output refresh
* fix the test code in libwallet
* rustfmt
* fix wallet_command_line test
* modify the warning message for self sending
* a bit of unit test according to review comments
* display unknown value for the case of multiple outputs on single receiver, normally it's not the case of this wallet implementation
* rustfmt
* fix merge missing parts
* rustfmt
* use PaymentCommitMapping struct instead of a tuple
* rustfmt
* fix the test
* fix the owner api rpc test
* add slate upgrading/downgrading
* add slate versions
* slate versioning compilation and tests
* transaction slate responses downgrade themselves to the version of the caller
* add command line arg for target slate version output
* v2 versioning comment info
* doctest fixes
