- eliminate CMake 3.5+ warnings
- removed usage of dropped "OPENCV_CAMERA_MODULES" variable
- partial support for Android NDK 11+

Epoch is gone; now the version component names in C++ and CMake
are consistent (except REVISION corresponds to PATCH).

Front/Back camera constants' values changed;
Additional camera facing check added for JavaCameraView.

Warning in auto generated code was suppressed by project settings.

OpenCV namespace added;
Default values for camera_id added;
Aditional constructor with cameraId added.
Resolution added to FPS message.

FPS meter added;
Camera switching posibility added;
Attributes loading for layout filed implemented.

- Adding Android SDK/ADT r21 compatibility;
- fixing stl headers path for new ndk;
- fixing native API level for Android projects

OpenCV info library name fixed;
Minimum API level for OpenCV library project increased up to 3 for using message dialogs.