Django-forms-plus

Features:
- new, experimental: Add "suggestions" feature to SlugInput
- new: Add "regexp" soft validator

Spec:
- enhancement, bc: change soft validators spec - introduce "name,value,inverse,message" structure

Backend:
- new: Add "dfp_field_name" optional attribute for Form Fields (to overwrite type of field during a spec generation)
- enhancement, bc: Process bound fields (instead of Form.fields) during a spec generation
- refactor, bc: Rename "django_forms_plus.fields" to "django_forms_plus.widgets"

Frontend:
- new: Add "regexp" soft validator

Backend, Spec:
- add support for custom validators
- add basic support for files uploading
- add custom widgets: SlugInput, ClearableFileInput, CroppedImageInput

Frontend:
- new: add ImageUpload component
- new: add InputSlug component
- deps: add "mui/base" NPM package (for "Crop image" modal window)
- deps: add "react-image-crop" NPM package (for "Crop image" modal window)
- internals: add submitResult, debugEnabled, rhf: {setValue, clearErrors} to FormContext.Provider

The initial release.