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/search_replace/mode_buttons.py

@@ -0,0 +1,75 @@
+# Python imports
+
+# Lib imports
+import gi
+gi.require_version('Gtk', '3.0')
+from gi.repository import Gtk
+
+# Application imports
+
+
+
+class ModeException(Exception):
+    ...
+
+
+
+class ModeButtons(Gtk.ButtonBox):
+    def __init__(self):
+        super(ModeButtons, self).__init__()
+
+        self.use_regex: bool    = False
+        self.match_case: bool   = False
+        self.in_selection: bool = False
+        self.whole_word: bool   = False
+
+        self._setup_styling()
+        self._setup_signals()
+        self._load_widgets()
+
+
+    def _setup_styling(self):
+        ctx = self.get_style_context()
+        ctx.add_class("search-replace-mode-buttons")
+
+    def _setup_signals(self):
+        ...
+
+    def _load_widgets(self):
+        use_regex_bttn    = Gtk.ToggleButton(label = ".*")
+        match_case_bttn   = Gtk.ToggleButton(label = "Aa")
+        in_selection_bttn = Gtk.ToggleButton()
+        whole_word_bttn   = Gtk.ToggleButton()
+
+        use_regex_bttn.set_sensitive(False)
+
+        use_regex_bttn.set_tooltip_text("Use Regex")
+        match_case_bttn.set_tooltip_text("Match Case")
+        in_selection_bttn.set_tooltip_text("Only In Selection")
+        whole_word_bttn.set_tooltip_text("Whole Word")
+
+        use_regex_bttn.connect("toggled", self._toggled_button, "use_regex")
+        match_case_bttn.connect("toggled", self._toggled_button, "match_case")
+        in_selection_bttn.connect("toggled", self._toggled_button, "in_selection")
+        whole_word_bttn.connect("toggled", self._toggled_button, "whole_word")
+
+        in_selection_bttn.set_image(
+            Gtk.Image.new_from_file("images/only-in-selection.png")
+        )
+        whole_word_bttn.set_image(
+            Gtk.Image.new_from_file("images/whole-word.png")
+        )
+
+        self.add(use_regex_bttn)
+        self.add(match_case_bttn)
+        self.add(in_selection_bttn)
+        self.add(whole_word_bttn)
+
+    def _toggled_button(self, toggle_button, mode: str):
+        setattr(self, mode, not getattr(self, mode))
+        self.request_update()
+
+    def request_update(self):
+        raise ModeException("Must by 'monkey' patched from search_replace.py") 
+
+