[1812] Update Docs and Fix Compat Layer

PLUGINS.md

@@ -1193,19 +1193,27 @@ widget if you need to display routine status information.
 ## Localisation
 
 You can localise your plugin to one of the languages that EDMarketConnector
-itself supports. Add the following import near the top of each source
+itself supports. Add the following boilerplate near the top of the source
 file that contains strings that needs translating:
 
 ```python
-from l10n import translations as tr
+import l10n
+import functools
+plugin_tl = functools.partial(l10n.translations.tl, context=__file__)
+
 ```
 
-Wrap each string that needs translating with the `tr.tl()` function, e.g.:
+Wrap each string that needs translating with the `plugin_tl()` function, e.g.:
 
 ```python
-    somewidget["text"] = tr.tl("Happy!")
+    somewidget["text"] = plugin_tl("Happy!")
 ```
 
+Note that you can name the "plugin_tl" function whatever you want - just make sure to stay consistent! 
+Many plugins use `_` as the singleton name. We discourage that in versions 5.11 onward, but it should still work.
+If your plugin has multiple files that need translations, simply import the `plugin_tl` function to that location.
+You should only need to add the boilerplate once.
+
 If you display localized strings in EDMarketConnector's main window you should
 refresh them in your `prefs_changed` function in case the user has changed
 their preferred language.

l10n.py

@@ -86,7 +86,7 @@ def install_dummy(self) -> None:
         """
         self.translations = {None: {}}
         # WARNING: '_' is Deprecated. Will be removed in 6.0 or later.
-        # Migrate to calling Translations.translate directly.
+        # Migrate to calling translations.translate or tr.tl directly.
         builtins.__dict__['_'] = lambda x: str(x).replace(r'\"', '"').replace('{CR}', '\n')
 
     def install(self, lang: str | None = None) -> None:  # noqa: CCR001
@@ -131,7 +131,7 @@ def install(self, lang: str | None = None) -> None:  # noqa: CCR001
                     logger.exception(f'Exception occurred while parsing {lang}.strings in plugin {plugin}')
 
         # WARNING: '_' is Deprecated. Will be removed in 6.0 or later.
-        # Migrate to calling Translations.translate directly.
+        # Migrate to calling translations.translate or tr.tl directly.
         builtins.__dict__['_'] = self.translate
 
     def contents(self, lang: str, plugin_path: str | None = None) -> dict[str, str]:
@@ -351,7 +351,7 @@ def __init__(self):
         super().__init__()
 
 
-Translations: Translations = _Translations()  # type: ignore # Yes, I know this is awful. But we need it for compat.
+Translations = translations  # Yes, I know this is awful renaming garbage. But we need it for compat.
 # End Deprecation Zone
 
 # generate template strings file - like xgettext