WIP: compiles but completely broken

AGG files imported from AGG repository, sdl-testing branch.

the pixfmt_bgra32_lcd is just implemented and is not tested.

notes.txt

@@ -0,0 +1,34 @@
+stbtt_InitFont
+
+stbtt_ScaleForMappingEmToPixels x 3
+stbtt_ScaleForPixelHeight
+stbtt_BakeFontBitmap
+stbtt_GetFontVMetrics x 2
+
+struct RenImage {
+  RenColor *pixels;
+  int width, height;
+};
+
+typedef struct {
+  RenImage *image;
+  stbtt_bakedchar glyphs[256];
+} GlyphSet;
+
+struct RenFont {
+  void *data;
+  stbtt_fontinfo stbfont;
+  GlyphSet *sets[MAX_GLYPHSET];
+  float size;
+  int height;
+};
+
+typedef struct {
+   unsigned short x0, y0, x1, y1; // coordinates of bbox in bitmap
+   float xoff, yoff, xadvance;
+} stbtt_bakedchar;
+
+The function stbtt_BakeFontBitmap is used to write bitmap data into set->image->pixels (where set is a GlyphSet).
+Note that set->image->pixels need data in RGB format. After stbtt_BakeFontBitmap call the bitmap data are converted into RGB.
+With a single call many glyphs corresponding to a range of codepoints, all in a
+single image.