This change adds utility code for calculating summaries from multiple samples (snapshots) of EnsoGL runtime stats values.
This internal feature is expected to be used by Enso IDE performance profiling tools, which are planned to be added in the near future.
https://www.pivotaltracker.com/story/show/181093920
A demo scene named `stats` was added, showcasing how to perform calculations using the new tools. Currently, the summary calculations in the scene work only when the EnsoGL stats Monitor Panel is visible; this is planned to be improved in a future task (https://www.pivotaltracker.com/story/show/181093601).
- Note: the stats aggregation code is intended to be later used in Enso IDE's main rendering loop, so it needs to have very good performance characteristics.
- Due to that, `Accumulator` was designed to only use simple addition arithmetic, and be constant-memory once created.
This PR adds `json-rpc` crate — a library facilitating writing clients using JSON-RPC 2.0 protocol.
This library is meant to be used in implementation of File Manager and, in future, of Language Server clients.
The library is agnostic about `Transport` — but the interface has been designed in compliance with web-sys websockets, as this will be primary platform.
The RPC clients implemented on top of this library are expected to provide Future-based asynchronous API.
Client is designed to work in a single-thread environment,
Implements #426.
AST lives in `ast` package, that relies significantly on `ast-macros` to generate boilerplate.
Additional `macro-utils` library was split out from `shapely-macros` and `ast-macros`.
The implementation was contributed by @wdanilo , I basically just did some refactoring, documenting and testing.
### Important Notes
* AST is known to be incomplete structurally, finishing it is #336
* AST is missing a number of necessary functions, some of them explicitly marked as FIXME in the code, finishing them is #338
* while I have written some tests, they are not yet part of CI — I want to this smart way (i.e. allowing tests that rely on parser), it is tracked as #340
* AST JSON serialization is incompatible with Scala, solving this is #297
* there is some non-deterministic issue with CI on Windows — I need to look into this closer but it seems to not be related to any Rust parts
