Refactor mesh handling to use templated vertex structures for improved type safety and flexibility

res/shaders/entity.glslv

@@ -3,7 +3,7 @@
 layout (location = 0) in vec3 v_position;
 layout (location = 1) in vec2 v_texCoord;
 layout (location = 2) in vec3 v_color;
-layout (location = 3) in float v_light;
+layout (location = 3) in vec4 v_light;
 
 out vec4 a_color;
 out vec2 a_texCoord;
@@ -31,7 +31,7 @@ void main() {
     vec3 pos3d = modelpos.xyz - u_cameraPos;
     modelpos.xyz = apply_planet_curvature(modelpos.xyz, pos3d);
 
-    vec4 decomp_light = decompress_light(v_light);
+    vec4 decomp_light = v_light;
     vec3 light = decomp_light.rgb;
     float torchlight = max(0.0, 1.0-distance(u_cameraPos, modelpos.xyz) / 
                        u_torchlightDistance);