Pydanclick

New features:

- Support nested models
- Support container types such as lists or dicts

Bug fixes:

- Avoid name collision by prefixing argument names with `prefix`

And also:

- Reorganize code
- Normalize prefix and aliases (i.e. accept with and without leading dashes)

First working version of `pydanclick`. Basic features are there, so the library should be usable as long as:

- you stay away from complex types (e.g. container types such as lists or dicts). As a workaround, you can `exclude` non-compatible fields and add them manually
- you're not using advanced Click features
- you don't use nested models