Splitted sideinf.hpp and sideinf.cpp into two new classes
model.cpp/model.hpp and evaluator.cpp/evaluator.hpp
moved io functions to internal namespace
moved sgd class to sideinf_model class
Moved io functions to internal namespace
minor changes..
Added header files for classes Model and SideinfModel
changed some variables names..
added tests and modified CMakeLists.txt accordingly
added keepPos function
changed macros names
added errors
removed colmajor
added struct WeightedItemSimilarityModel
added WeightedItemSimilarityModel struct
removed #ifdef COLMAJOR