Factor out more resources.

+ Use QOpenGLShader to get compiled shader code in TreeView.
+ Remove last remaining Qt resources dependency in libqtk.
+ shaders.h in libqtk to define default GLSL shader programs.

resources/shaders/fragment/model-basic.frag

@@ -1,11 +0,0 @@
-#version 330 core
-out vec4 fColor;
-
-in vec2 vTextureCoord;
-
-uniform sampler2D texture_diffuse1;
-
-void main()
-{
-    fColor = texture(texture_diffuse1, vTextureCoord);
-}

resources/shaders/fragment/multi-color.frag

@@ -1,9 +0,0 @@
-#version 330
-in vec4 vColor;
-
-out vec4 fColor;
-
-void main()
-{
-  fColor = vColor;
-}