Add touchscreen support with onscreen keyboard (#1)

Possible that framebuffer doesn't update without actual keypress (eg, volume down). But, works.

src/essential/mod.rs

@@ -3,6 +3,7 @@ pub mod taskbar;
 pub mod lock_screen;
 pub mod workspace_indicator;
 pub mod start_menu;
+pub mod onscreen_keyboard;
 
 pub mod about;
 pub mod help;