Appcli

Feature
* Use classes for grouping; add CompositeConfig and CallbackConfig ([`751630f`](https://github.com/kalekundert/appcli/commit/751630fba26ff1c3ee63966f098886203efe2012))

Fix
* Exclude inactive layers when looking up parameter values ([`6b1433c`](https://github.com/kalekundert/appcli/commit/6b1433ca9765d6814043cd2092d7c8ee1a9ba8bf))

Feature
* Add ArgparseConfig ([`6594f3c`](https://github.com/kalekundert/appcli/commit/6594f3c99844825d285828ae37f3dbcc6cda05c7))

Documentation
* Add a brief description of the project ([`10e46e2`](https://github.com/kalekundert/appcli/commit/10e46e25f27c61e767dd252d9aa8cca177051ae5))