Update to allow loading data from a .csv file that only contains training samples values and not the associated responses. To allow this behavior, function must be called with parameters ResponsesStartIdx <= -2 and ResponsesEndIdx = 0

- added test for loading legacy files
- added version to new written models
- fixed loading of several fields in some models
- added generation of new fields from old data

1. someMatrix.data -> someMatrix.prt()
2. someMatrix.data + someMatrix.step * lineIndex -> someMatrix.ptr( lineIndex )
3. (SomeType*) someMatrix.data -> someMatrix.ptr<SomeType>()
4. someMatrix.data -> !someMatrix.empty() ( or !someMatrix.data -> someMatrix.empty() ) in logical expressions

initial commit; ml has been refactored; it compiles and the tests run well; some other modules, apps and samples do not compile; to be fixed

This reverts commit 4d36be87.

Conflicts:
	modules/ml/include/opencv2/ml/ml.hpp
	modules/ml/src/data.cpp

This reverts commit a8c5e356.

Conflicts:
	modules/imgproc/src/imgwarp.cpp

fixed several typos in docs; make MLData capable of reading csv files with much more columns than before