New lightmapper

-Added LocalVector (needed it)
-Added stb_rect_pack (It's pretty cool, we could probably use it for other stuff too)
-Fixes and changes all around the place
-Added library for 128 bits fixed point (required for Delaunay3D)

modules/xatlas_unwrap/register_types.cpp

@@ -137,6 +137,7 @@ bool xatlas_mesh_lightmap_unwrap_callback(float p_texel_size, const float *p_ver
 
 	pack_options.maxChartSize = 4096;
 	pack_options.blockAlign = true;
+	pack_options.padding = 1;
 	pack_options.texelsPerUnit = 1.0 / p_texel_size;
 
 	xatlas::Atlas *atlas = xatlas::Create();