Gambatte-K2 - Game Boy / Game Boy Color emulator

- Fast, Lightweight UI:
Minimal dependencies (`2.5Mb` binary), runs pretty well on low-RAM e-ink Kindles using around `15Mb` of RAM.
- Two Rendering Modes:
- GTK2:Standard X11/GTK2 drawing mode using the OS e-ink refreshing.
- FBInk:Direct framebuffer output for maximum speed, a little quirky, with more ghosting.
- Performance-Oriented Design:
- Only one main loopin the frame processing path doing scaling and dithering at once.
- Ordered dithering (BW)(Bayer 4x4) applied during a first scaling stage for improved frame speed processing.
- Nearest-neighbor scalingin the second stage for fast upscaling.
- Single GdkPixbufreused for all frames to minimize RAM usage and allocations.
- LUT (Lookup Table):Precomputed 65536-entry lookup table with RGB565→RGB888→grayscale conversion for fast pixel processing.
- Touch & Multi-Touch Controls:
- On-screen virtual Game Boy like buttons with ad-hoc multi-touch support (up to 2 touches) listening directly on the /dev/input/eventX device events.
- Dynamic Quality/Size Controls:
- Toggle between some scaling/quality presets.
- Threaded Frame Processing:
- Frame conversion and drawing are offloaded to a worker thread to keep the UI responsive.
- Minimal External Dependencies:
- Only needs GTK2, GDK-Pixbuf, and FBInk (for direct mode).