Fixed conflicts after merge with master

resources/shaders/mm_contour.fs

@@ -0,0 +1,11 @@
+#version 110
+
+const float EPSILON = 0.0001;
+
+void main()
+{
+    gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0);
+    // Values inside depth buffer for fragments of the contour of a selected area are offset
+    // by small epsilon to solve z-fighting between painted triangles and contour lines.
+    gl_FragDepth = gl_FragCoord.z - EPSILON;
+}

resources/shaders/mm_contour.vs

@@ -0,0 +1,6 @@
+#version 110
+
+void main()
+{
+    gl_Position = ftransform();
+}

resources/shaders/printbed.vs

@@ -1,12 +1,14 @@
 #version 110
 
-attribute vec4 v_position;
+attribute vec3 v_position;
 attribute vec2 v_tex_coords;
 
 varying vec2 tex_coords;
 
 void main()
 {
-    gl_Position = gl_ProjectionMatrix * gl_ModelViewMatrix * v_position;
+    gl_Position = gl_ModelViewProjectionMatrix * vec4(v_position.x, v_position.y, v_position.z, 1.0);
+	// the following line leads to crash on some Intel graphics card
+    //gl_Position = gl_ModelViewProjectionMatrix * vec4(v_position, 1.0);
     tex_coords = v_tex_coords;
 }