Implements language selection properly

Adds a configuration option for the plugin language
Loads the selected language instead of always loading "en"
Makes sure the language is updated upon reloading

README.md

@@ -108,6 +108,12 @@ All currently supported presets, and available filters for each preset:
 
 ## Configuration options
 
+### Plugin Options
+
+| Key | Value type | Description |
+| --- | --- | --- |
+| language | string | The language used for this plugin. Only "en" is supported, unless you add a custom language. |
+
 ### Global-only options
 
 | Key | Value type | Description |