* Update G-API code base to 27-Sep-18

Changes mostly improve standalone build support

* G-API code base update 28-09-2018

* Windows/Documentation warnings should be fixed
* Fixed stability issues in Fluid backend
* Fixed precompiled headers issues in G-API source files

* G-API code base update 28-09-18 EOD

* Fixed several static analysis issues
* Fixed issues found when G-API is built in a standalone mode

* fix build warnings

* python: forbid wrapping of functions with "void*" arguments

Fixes for instrumentation of IPP and OCL (#12637)

* fixed warning about re-declaring variable when both IPP and instrumentation are enabled

* fixed segfault when no funName provided

* compilation fixed when both OCL and instrumentation are enabled

* dnn(ocl4dnn): update kernel checks

* dnn: workaround for IDLF kernels on Intel iGPU

* dnn(test): remove "skip" check for unstable cases

* G-API Initial code upload

* Update G-API code base to Sep-24-2018

* The majority of OpenCV buildbot problems was addressed

* Update G-API code base to 24-Sep-18 EOD

* G-API code base update 25-Sep-2018

* Linux warnings should be resolved
* Documentation build should become green
* Number of Windows warnings should be reduced

* Update G-API code base to 25-Sep-18 EOD

* ARMv7 build issue should be resolved
* ADE is bumped to latest version and should fix Clang builds for macOS/iOS
* Remaining Windows warnings should be resolved
* New Linux32 / ARMv7 warnings should be resolved

* G-API code base update 25-Sep-2018-EOD2

* Final Windows warnings should be resolved now

* G-API code base update 26-Sep-2018

* Fixed issues with precompiled headers in module and its tests

* cmake: js cleanup

- avoid unnecessary 2 messages for other platforms
- drop MODULE_NAME variable

* js: cleanup build_js.py

* Remove isIntel check from deep learning layers

* Remove fp16->fp32 fallbacks where it's not necessary

* Fix Kernel::run to prevent localsize > globalsize

* Fix #12542

* Remove ignore of non-virtual-dtor error

* M_PI changed to CV_PI

* M_PI changed to CV_PI

* M_PI changed to CV_PI

findChessboardCornersSB: speed improvements (#12615)

* chessboard: fix do not modify const image

* chessboard: speed up scale space using parallel_for

* chessboard: small improvements

* chessboard: speed up board growing using parallel_for

* chessboard: add flags for tuning detection

* chessboard: fix compiler warnings

* chessborad: change flag name to CALIB_CB_EXHAUSTIVE

This also fixes a typo

* chessboard: fix const ref + remove to_string