Fixed MinGW build by declaring the minimal required Windows version.

Also deleted miscellaneous remaining multimon cruft.
Deleted #include <winuser.h>, because <windows.h> includes it
already.

This should have a nice side effect of preventing us from
accidentally using any Windows API that's too new.
Merge pull request #2094 from SpecLad:multimon-be-gone
fixed bug #3319
Merge pull request #2084 from ilya-lavrenov:cont
Fix algorithm setter argument validation for uchar
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
Fix typo of SparseMat_<_Tp>::SparseMat_(const SparseMat& m)

Fix compilation erros when compiling this constructor.
First argument type of "convertTo" should be instance, not a pointer of instance.

First pull request was created for master branch.
But it should be marged for 2.4.
https://github.com/Itseez/opencv/pull/2113
Fixed a valgrind 'Conditional jump or move depends on uninitialised value(s)' on cv::kmeans(...). The original code used points(sampleCount, 1, CV_32FC2), which confused generateCentersPP into thinking it is a 1 dimensional center, instead of 2. As a result it would set only the x variable and leave y unitialised.
deleted extra semicolons
Merge pull request #2114 from kazuki-ma:SparseMat_convertTo_typofix_24
Merge pull request #2106 from robbertkl:patch-2
Removed unecessary initialisation of Mat centers.
Merge pull request #2118 from ilya-lavrenov:semicolons
Merge pull request #2115 from nghiaho12:kmeans_sample
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