Based on pull request #685

Set ptr to NULL, so this method can be called repeatedly. This fixes a crash after unplugging web cam and trying to re-scan the cameras.

Fixed flann build with NEON;
Fixed Haming distance with NEON;
Honest cvRound for WinRT added;
cvRound test added;
Video IO with direct show disabled;

Warnings fix;

TIFF build was fixed;
Direct Show back-end was enabled;
More accurate guards implemented.

GPU module turned off;
TIFF support turned off;
Windows Managment and Video IO (VFW) turned off.

- libavcodec issue
- some decoders alter AVCodecContext width/height values, in a wrong way
- eg. in issue 2815, vp6f decoder changes these values, resulting in distorted / invalid frames
- this patch forces default AVCodecContext values

* removed OpenGLFuncTab, now extensions are loaded internally
* added support of GlBuffer and GlTexture2D to InputArray/OutputArray
* added ELEMENT_ARRAY_BUFFER and PIXEL_PACK_BUFFER targets
* added copyFrom/copyTo method for GlBuffer and GlTexture2D
* removed GlFont
* removed pointCloudShow
* removed OpenGLCleanCallback
* added Access parameter to GlBuffer::mapHost
* added autoRelease parameter to all create methods

This reverts commit 4abf0b31.

Changes are reverted because they break build of proxy dlls on Windows

HardFP and SoftFP toolchains joined to one;
RPATH skiping added.

Issue #2114

Added test checking that all valid fourcc values are converted properly

Сonflict exists between some versions of libtiff and opencv headers