unneeded cast
explicit cast from CvMat* to cv::Mat
add missing ClassWeights option to train_auto
fix balanced as a bool option
VarIdx and SampleIdx options parsing

they could be specified as either vector of integer indices or logical mask
enable predict options
minor edits
expose new predict_all function

the underlying implementation uses a parallel_for loop instead of
predicting the samples serially
update help of SVM
disable check of CvParamGrid in getGrid() function

this is becuase train_auto() method permits setting step=0 to disable
optimizing a certain parameter. Also the check is not really needed
since the train method will also do it.
factor common data in tests
more SVM tests