add dialog to manage highlighters

- no support for "no color"
- settings not saved to disk

hbox.py

@@ -0,0 +1,9 @@
+from PyQt6.QtWidgets import QWidget, QHBoxLayout
+
+
+class HBox(QWidget):
+    def __init__(self, *widgets: QWidget):
+        super(HBox, self).__init__()
+        self.layout = QHBoxLayout(self)
+        for widget in widgets:
+            self.layout.addWidget(widget)