[v1.7.3] Firefox compability patch (#32)

- Added Firefox support (#28)
- Updated settings defaults
- Updated `about:` protocol behavior
- Fixed collections header becoming the old one on a tab removing
- Added VS Code debugging config
- Removed trailing whitespaces

.vscode/launch.json

@@ -0,0 +1,13 @@
+{
+	"version": "0.2.0",
+	"configurations":
+	[
+		{
+			"name": "Debug",
+			"type": "firefox",
+			"request": "launch",
+			"reAttach": true,
+			"addonPath": "${workspaceFolder}"
+		}
+	]
+}