Extend set of samples (#296)

+ 12_InitFrameBuffers, 13_InitVertexBuffer, 14_InitPipeline, 15_DrawCube;
+ extend utilities and add utilities on geometries, math, and shaders
+ slightly adjust some other samples

samples/11_InitShaders/CMakeLists.txt

@@ -17,11 +17,13 @@ cmake_minimum_required(VERSION 3.2)
 project(11_InitShaders)
 
 set(HEADERS
+  ../utils/shaders.hpp
   ../utils/utils.hpp
 )
 
 set(SOURCES
   11_InitShaders.cpp
+  ../utils/shaders.cpp
   ../utils/utils.cpp
 )