Added some useful postprocessing shaders

Shaders come in two flavours:
- shaders/gl330: OpenGL 3.3+ (Windows, Linux, OSX)
- shaders/gles100:  OpenGL ES 2.0 (Android, RPI, HTML5)

shaders/gl330/template.fs

@@ -0,0 +1,19 @@
+#version 330
+
+in vec2 fragTexCoord;
+
+out vec4 fragColor;
+
+uniform sampler2D texture0;
+uniform vec4 tintColor;
+
+// NOTE: Add here your custom variables
+
+void main()
+{
+    vec4 texelColor = texture2D(texture0, fragTexCoord);
+    
+    // NOTE: Implement here your fragment shader code
+    
+    fragColor = texelColor*tintColor;
+}