Make values parameter in OneOf to be variadic (#12)

This PR alters the signature of `validate.OneOf` function so that its
second parameter, `values`, becomes a variadic parameter instead of a
flat slice type.

This aims to improve the experience of restraining values.

Add multipart form support (#10)

Add more examples to docs

Adding examples

Optimize allocations for parameters

Optimize allocations

Add documentation

Add linting

Add tests for lit.Request

Merge pull request #1 from jvcoutinho/feature/result-package

Result package