Split framebuffer functions into library

src/libmittos/include/graphics.h

@@ -0,0 +1,19 @@
+#pragma once
+#include <stdlib.h>
+
+typedef struct {
+    uint32_t width;
+    uint32_t height;
+    uint32_t bpp;
+    uint32_t pitch;
+    void *addr;
+    void *buffer;
+    size_t size;
+} gfx_context;
+
+#define RGB(r, g, b) (((uint32_t) (r<<16) + (g<<8) + (b)))
+
+void putpixel(gfx_context *ctx, uint64_t x, uint64_t y, uint32_t clr);
+void putCharacter(gfx_context *ctx, uint64_t x, uint64_t y, uint32_t clr_fg, uint32_t clr_bg, char c);
+void flip(gfx_context *ctx);
+gfx_context *framebuffer_make_subcontext(gfx_context *ctx, uint64_t x, uint64_t y, uint64_t width, uint64_t height);