weights array is only allocated for (l_count+1) elements,
but then weights[l_count+1] element is accessed.

This should allow many algorithms to take advantage of more parallelization
technologies.

a big patch; use special proxy types (Input/OutputArray, Input/OutputArrayOfArrays) for passing in vectors, matrices etc.

replaced alloca() (a.k.a. cvStackAlloc) with AutoBuffer or vector() everywhere. cvStackAlloc() is still defined, but we do not need alloca() anymore to compile and run OpenCV (fixes #889 and may be some others)