Configpile

Fix

- **processor**: add context in collector errors too

Feat

- **errors**: add context in error reporting

Fix

- **config**: let argparse handle positional arguments for help display

Fix

- **processor**: fix typo

Feat

- **errors**: renamed collect_optional->collect, added collect_optional that collects a seq of Optional[Err]
- **config**: add post-construction config validation with error reporting

BREAKING CHANGE

- Renamed collect_optional->collect, collect->collect_non_empty

Feat

- **types**: add ParamType.map/as_sequence_of_one
- add reexport of common identifiers
- **types**: added float parameter type

Fix

- **processor**: make config file paths relative
- **arg**: correct bug in ParamType.append