* Bump to 0.15.0
* Add new distant-ssh2 subcrate to provide an alternate session as an ssh client
* Add rpassword & wezterm-ssh dependencies
* Rename core -> distant-core in project directory structure and move ssh2 feature into distant-ssh2 crate
* Upgrade tokio to 1.12,
* Update github actions to detect changes and apply testing for only those changes
* Add method parameter to support distant & ssh methods for action and lsp subcommands
* Add ssh-host, ssh-port, and ssh-user parameters to specify information for ssh method
* Add `SessionExt` trait for friendlier methods
* Create `Mailbox` and internal `PostOffice` to manage responses to requests
* Refactor `Session` to use a new `SessionChannel` underneath
* Refactor `Response` to always include an origin_id field instead of being optional
* Update `ProcStdout`, `ProcStderr`, and `ProcDone` to include origin id
* Replace `verbose` option with `log-level`
* Remove DistantCodec
* Add Codec trait to support encode & decode
* Add XChaCha20Poly1305 dependency in place of orion
* Add XChaCha20Poly1305Codec that encrypts/signs using XChaCha20Poly1305
* Add PlainCodec that does no encrypting/signing
* Refactor Transport to take generic Codec
* Rewrite to no longer use blake256
* Remove k256 dependency
* Remove Transport::from_handshake as no longer doing EDCH key exchange
* Fix stdout/stderr being sent before proc_start by adding post_hook support to handler such that proc_run tasks are not spawned until proc_start is sent as response
* Remove unneeded else if condition when checking join error type
Chip Senkbeil