Add IPP support in cvtColor function
Fix a bug of retinaParameters.
When colorMode is set to 0 via Retina::_init method, _retinaParameters's
colorMode variable is not correctly assigned.
macros -> template in IPP support cvtColor
Make some tweaks to make `sum` operations less frequently
Fix build error.
Remove trailing whitespace.
gpu TVL1 Optical Flow optimization:

do not calculate sum of error in every round of iteration;
instead the error will be summed every 2nd times or more, 
if the previous sum of error is too far away from threshold.
Merge pull request #1346 from jet47:gpu-tvl1-optimization
Restored one executable bit that was lost during the war on whitespace.
appended ocl::finish to test_cycle defines
rewrite gpu stereo multi gpu sample:

* use different approaches -> threads and streams
* clean up code
Merge pull request #1349 from ilya-lavrenov:ocl_perf_finish
Deleted the now-empty ocl perf_precomp.cpp.

See pull request #1241 for why.
Merge pull request #1213 from kdrobnyh:color
Merge pull request #1357 from SpecLad:less-precomps
Bug #3238 Android sample image manipulations blinks in non-preview modes fixed.
New Tegra detector with Android 4.3 support added. Manager version++.
fixed building OpenCV with IPP 6.x (different DFT API); added Canny and rectangular morphology (based on Alex Kapustin patches)
LibTIFF Win32 API back-end disabled for Windows RT.
Merge pull request #1343 from asmorkalov:android_img_manipulations_fix