Introduce {% fill %} replacing 'fill' func of 'slot' tag

Partial implementation fill-tags plus update tests

Implement {% fill %} tags. Next: update tests.

Bring back support for {%slot%} blocks for bckwrd-compat and implement ambig. resolution policy

Update tests to use fill blocks. Add extra checks that raise errors

Add new tests for fill-slot nesting

Update README. Editing still required

remove unused var ctxt after flake8 complaint

fix flake8 warning about slotless f-string

[pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Add new slot aliases in fill context. Clean up rendering logic in Component. Update docs.

fix flake8, isort, black errors

Refactor duplicated name validation

Add if_filled tag + elif_filled...else_filled...endif_filled for cond. slots

Fix mistake in do_if_filled() docstring

Upload templates for tests! D'oh

Incorporate PR feedback

Drop Literal type hint; Use isort off-on instead of skip in tests

Treat all fill,slot,if_filled,component names as variables

Reset sampleproject components

Add test for variable filled name

Update examples in docs

django_components/app_settings.py

@@ -1,5 +1,3 @@
-import sys
-
 from django.conf import settings
 
 
@@ -19,7 +17,11 @@ class AppSettings:
     def TEMPLATE_CACHE_SIZE(self):
         return self.settings.setdefault("template_cache_size", 128)
 
+    @property
+    def STRICT_SLOTS(self):
+        """If True, component slots that are declared must be explicitly filled; else
+        a TemplateSyntaxError is raised."""
+        return self.settings.setdefault("strict_slots", False)
+
 
 app_settings = AppSettings()
-app_settings.__name__ = __name__
-sys.modules[__name__] = app_settings