Add status bar (that can be hidden) at the bottom of the screen with useful info

[MBilderbeek]

Missing there compared to Catapult is the FPS indicator.

Other stuff that can be added:

• running software
• main properties of the current machine (RAM, VRAM)
• current screen mode
• CPU usage? (As seen in some other emulators.)

It must definitely be possible to hide this bar.

[MBilderbeek]

I think this feature is done for now.