add versions to new shaders

examples/models/resources/shaders/glsl100/voxel_lighting.fs

@@ -1,3 +1,4 @@
+#version 100
 #ifdef GL_ES
 precision mediump float;
 #endif

examples/models/resources/shaders/glsl100/voxel_lighting.vs

@@ -1,3 +1,4 @@
+#version 100
 #ifdef GL_ES
 precision mediump float;
 #endif

examples/models/resources/shaders/glsl120/voxel_lighting.fs

@@ -1,3 +1,4 @@
+#version 120
 // Input from vertex shader
 varying vec3 fragPosition;
 varying vec4 fragColor;

examples/models/resources/shaders/glsl120/voxel_lighting.vs

@@ -1,3 +1,4 @@
+#version 120
 // Input vertex attributes
 attribute vec3 vertexPosition;
 attribute vec3 vertexNormal;