fixed Bug #2581

GoodFeaturesToTrackDetector_GPU fails when no corners found

Increased time limits for perf tests

Android: always sort list of NDK toolchains

Order returned by CMake is unreliable but we need clang to go after gcc for
automatic toolchain selection.

In tutorial-1 fps meter enabled via layout.xml. Camera id is set to "any" via lauout.xml;
In tutorial-2 message moved ion the bottom of the screen.

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.

(#2569) simplifying code to avoid Eclipse CDT editor confusion, removing warnings and typos in comments

* do not lose auto-selected device while running several tests
* reduce output noise
* list available devices if unable to auto-select device
* fix error message when no devices connected