Revert a hack for shadows.

It helps for horizontal surfaces, but makes vertical surfaces worse (for example rocks in cornfield crossing), so it's not really a solution.

data/shaders/sunlightshadow.frag

@@ -36,9 +36,7 @@ float getShadowFactor(vec3 pos, int index)
     {
         for (float j = -1.; j <= 1.; j += 1.)
         {
-            // result += texture(shadowtex, vec4(shadowtexcoord + vec2(i,j) / shadow_res, float(index), d));
-            // Added a hack with j+1. to avoid ugly lines
-            result += texture(shadowtex, vec4(shadowtexcoord + vec2(i,j+1.) / shadow_res, float(index), d));
+            result += texture(shadowtex, vec4(shadowtexcoord + vec2(i,j) / shadow_res, float(index), d));
         }
     }