Add theme property to Utils

Gets set to the window.theme when a theme is loaded, done to avoid
having to refer to the window object from utils.

src/gui/PythonBridge/PythonBridge.qml

@@ -67,6 +67,7 @@ Python {
             window.uiState  = uiState
             window.history  = history
             window.theme    = Qt.createQmlObject(theme, window, "theme")
+            utils.theme     = window.theme
 
             if (callback) { callback(settings, uiState, theme) }
         })

src/gui/Utils.qml

@@ -6,6 +6,8 @@ import CppUtils 0.1
 QtObject {
     enum Media { Page, File, Image, Video, Audio }
 
+    property QtObject theme: null
+
     readonly property var imageExtensions: [
 		"bmp", "gif", "jpg", "jpeg", "png", "pbm", "pgm", "ppm", "xbm", "xpm",
 		"tiff", "webp", "svg",