Django-forms-plus

new, js: Add window.dfp global variable
new, js: Add "dfp:init" JS event
new, js: Add "dfp:onsubmit" JS event
enhancement, js: Add "position" setting to "success message"

new: Add support for django.forms.Select widget
new: Add "additional custom CSS-classes in widget" feature

bc, js: Don't do reset() if a form gets an empty payload in a response (for now)

fix: Several bug fixes
dev: Add "ruff" linter

- new: Add masked input feature to TextInput widget
- new: Add "date" (DateInput) field
- enhancement: Add "allow_empty" setting to regexp validators

Backend:
- enhancement: Allow set a custom widget name via "dfp_widget_name" attribute
- enhancement: Add FormattedInput widget

Spec:
- bc, new: Support "regexp" validators + change spec in "validators / soft_validators"
- bc: Remove "placeholders" section (use `Meta.widgets[WIDGET].attrs instead)

Backend:
- fix: Copy (shallowly) dict props of Dfp meta instead of just getting a link var to a same dict

Frontend:
- enhancement: Apply to 'slug' field type the same rules as for 'text' type during validation on frontend

- fix: Fix displaying of server validation errors