fixing bug #3345
Improved documentation for neural network
Fix: freeing previous elements has to be done before loading new parameters to avoid trying to delete unexisting objects if arrays size was modified
Corrected package name in tutorial

See also #2101
'master'-like Haar perf test
Merge pull request #2132 from ComFreek:patch-2
updated .gitignore
refactoring the test as it should be in 2.4
Added throwing exception when saving untrained SVM model
Merge pull request #2108 from pemmanuelviel:flannMemoryLeak
Merge pull request #2137 from ilya-lavrenov:gitignore
adding `finish()` to flush CL queue, renaming the test to match 'master' branch
Fix the following error for ocl::getOpenCLPlatforms() on Ubuntu 12.04 with gcc 4.8
OpenCV Error: Unknown error code -6 (OpenCL function is not available: [clGetPlatformIDs]) in opencl_check_fn, file /home/ahb/software/opencv/modules/ocl/src/cl_runtime/cl_runtime.cpp, line 83

The issue results from modules/ocl/src/cl_runtime/cl_runtime.cpp checking for
"linux" instead of "__linux__" (cp.  http://sourceforge.net/p/predef/wiki/OperatingSystems/)

Adjust all other occurrences of "defined(linux)" as well.
Merge pull request #2133 from apavlenko:2.4-perf_haar
Merge pull request #2145 from andreasBihlmaier:2.4
fixing bug #3345. don't use BORDER_ISOLATED alone. it should be combined with some border type
Fixed cvtColor alpha channel docs
Merge pull request #2143 from Daniil-Osokin:fix_docs_cvt_color_alpha_channel
Revert "fixed bug #3319"

See 092f916 for explanation.

This reverts commit 4f9c081dc313f8fdfee3f0a4572779ae13e27e40.
Re-fix bug #3319 with less side effects.