The right way to do this is probably to put the contracts onto the classpath before execution of the contract. However, this interacts closely with the sandboxing work, which isn't yet started, so for now this will do.
The progress tracker API lets you model a tree of steps, along the same structure as protocols and subprotocols. Each step has an (optionally changing) label, and thus progress trackers can be arranged in a tree. Updates to the progress at each level flow up the tree via an RxJava observable (I guess we will use this more in future).
A simple console renderer is provided that uses ANSI escapes and Emoji to show animated progress through a protocol.
The trader demo is enhanced to use this framework, when run outside of Gradle.
* Dependency resolution/checking is now working on both sides of the two party trading protocol.
* The commercial paper contract was changed to check timestamping authority identities by name instead of key.
* The trader demo has been rewritten to use the protocol framework, which simplifies the code.
This commit is incomplete: only the seller side currently checks. The code will be refactored out into subprotocols in further commits.
Note that timeouts are currently unhandled.
