Virtual keyboard + configuration:

- complete implementation of virtual keyboard
- support loading user defined virtual keyboard from configuration at $XDG_CONFIG_HOME/xkb/
- support loading user defined CSS theme from $XDG_CONFIG_HOME/themes/

resources/session-shell.css

@@ -0,0 +1,11 @@
+@import url("resource:///dev/iohub/diya/shell/virtual-keyboard.css");
+
+#diya_shell_launcher
+{
+    background-color: orange;
+}
+#diya_shell_background
+{
+    background-image:url("file:///etc/xdg/labwc/wpp.jpg");
+    background-size: cover;
+}