complete the implementation of LaplacianInferenceMethodWithLBFGS
we need to set the private data members in LaplacianInferenceMethod to be protected
remove the useless header file
add some comments in CLogitLikelihood
chang the order of matrix multiplication to gain improvement
Merge pull request #1970 from mazumdarparijat/pca

id3 tree added
Remove inline in CContingencyTableEvaluation 

CContingencyTableEvaluation::get_evaluation_direction function was defined as an inline in the implementation. this caused problems by compilation errors of modular interfaces.
thanks for the bug report Wenlin Hu!
fixed memory leaks from unit-test LogDetEstimator.Sparse_sample #1989
enable unit test
remove the useless code optimization for matrix mulitiplication
updated the L-BFGS class
add unit test for L-BFGS used the same result produced by the Newton method
Merge branch 'develop' of https://github.com/shogun-toolbox/shogun into feature/1868
removed unused ignore folder
Code format modify.
Merge pull request #1983 from pl8787/develop

#1931 HSIC unit test added.
Merge pull request #1992 from sunil1337/memleak

fixed memory leaks from unit-test LogDetEstimator.Sparse_sample #1989
Revert "remove the useless code optimization for matrix mulitiplication"

This reverts commit 1c39d9b2ac6a467482b0cb514c766d3c6c885001.
Revert "chang the order of matrix multiplication to gain improvement"

This reverts commit 7b8cf6d68433710e7aa10139e04b79c2b70d2c9e.
Revert "enable unit test"

This reverts commit 9babe6542d10c65feb00bff820f00b6d14a40ab0.