- removed tr1 usage (dropped in C++17)
- moved includes of vector/map/iostream/limits into ts.hpp
- require opencv_test + anonymous namespace (added compile check)
- fixed norm() usage (must be from cvtest::norm for checks) and other conflict functions
- added missing license headers

merged background color with background gradient methods, updated tests to show description of scene

delete common.h, viz_types.hpp, rendering properties are public, setcolor in creating_widgets tutorial

camera position widget: constructor with no parameter, constructor with intrinsic matrix for visualizing frustum