Moved plugins and refactor command system

- Moved plugins to apropriate sub folders
- Refactor command system with new add_command method and rename GetCommandSystemEvent to GetNewCommandSystemEvent
- Add RegisterCommandEvent for dynamic command registration
- Change footer container orientation to VERTICAL
- Add search-highlight tag to source buffer
- Add file change detection (deleted, externally modified) in source_file
- Add JSON prettify option to source view popup menu
- Enable hexpand on VTE widget
- Update plugins_controller_mixin to use widget_registry

plugins/code/commentzar/mixins/__init__.py

@@ -0,0 +1,3 @@
+"""
+    Pligin Module Mixin
+"""

plugins/code/commentzar/mixins/code_comment_tags_mixin.py

@@ -0,0 +1,30 @@
+# Python imports
+
+# Lib imports
+
+# Application imports
+
+
+
+class CodeCommentTagsMixin:
+    def get_comment_tags(self, language):
+        start_tag, end_tag = self.get_line_comment_tags(language)
+        if (start_tag, end_tag) == (None, None):
+            start_tag, end_tag = self.get_block_comment_tags(language)
+
+        return start_tag, end_tag
+
+    def get_block_comment_tags(self, language):
+        start_tag = language.get_metadata('block-comment-start')
+        end_tag   = language.get_metadata('block-comment-end')
+
+        if start_tag and end_tag: return (start_tag, end_tag)
+
+        return (None, None)
+
+    def get_line_comment_tags(self, language):
+        start_tag = language.get_metadata('line-comment-start')
+
+        if start_tag: return (start_tag, None)
+
+        return (None, None)