Remove tabs UI from code editor and move to plugin. Enhance plugin system.

- Remove tabs controller, tab widget, and tabs widget files and move to plugin
- Delete plugins/README.txt
- Add register_controller method to controller system for plugin use
- Add error handling for plugin crashes via futures callback

plugins/code/tabs_bar/tabs_controller.py

@@ -0,0 +1,75 @@
+# Python imports
+
+# Lib imports
+import gi
+
+from gi.repository import Gtk
+
+# Application imports
+from libs.controllers.controller_base import ControllerBase
+from libs.event_factory import Event_Factory, Code_Event_Types
+
+from core.widgets.code.source_view import SourceView
+
+from .tabs_widget import TabsWidget
+from .tab_widget import TabWidget
+
+
+
+
+class TabsController(ControllerBase):
+    def __init__(self):
+        super(TabsController, self).__init__()
+
+        self.tabs_widget: TabsWidget = TabsWidget()
+        self.tabs_widget.message     = self.message
+
+
+    def _controller_message(self, event: Code_Event_Types.CodeEvent):
+        if isinstance(event, Code_Event_Types.FocusedViewEvent):
+            self.tabs_widget.view_changed( event.view.get_buffer() )
+        elif isinstance(event, Code_Event_Types.FilePathSetEvent):
+            self.update_tab_label(event)
+        elif isinstance(event, Code_Event_Types.ModifiedChangedEvent):
+            self.tabs_widget.modified_changed( event.buffer )
+        elif isinstance(event, Code_Event_Types.FileExternallyDeletedEvent):
+            self.tabs_widget.externally_deleted( event.buffer )
+        elif isinstance(event, Code_Event_Types.AddedNewFileEvent):
+            self.add_tab(event)
+        elif isinstance(event, Code_Event_Types.PoppedFileEvent):
+            ...
+        elif isinstance(event, Code_Event_Types.RemovedFileEvent):
+            self.remove_tab(event)
+    
+    def get_tabs_widget(self):
+        return self.tabs_widget
+
+    def update_tab_label(self, event: Code_Event_Types.FilePathSetEvent):
+        for page_widget in self.tabs_widget.get_children():
+            tab = self.tabs_widget.get_tab_label(page_widget)
+            if not event.file == tab.file: continue
+
+            tab.label.set_label(event.file.fname)
+
+            break
+
+    def add_tab(self, event: Code_Event_Types.AddedNewFileEvent):
+        tab      = TabWidget()
+        tab.file = event.file
+
+        tab.label.set_label(event.file.fname)
+
+        self.tabs_widget.append_page(Gtk.Separator(), tab)
+        tab.show_all()
+
+    def remove_tab(self, event: Code_Event_Types.RemovedFileEvent):
+        for page_widget in self.tabs_widget.get_children():
+            tab = self.tabs_widget.get_tab_label(page_widget)
+            if not event.file == tab.file: continue
+
+            tab.clear_signals_and_data()
+            self.tabs_widget.remove_page(
+                self.tabs_widget.page_num(page_widget)
+            )
+
+            break