Intro nb added
clean up and regression
preprocessor example
Regression nb
lars section
some more additions
revamp structure
using small dataset
fix the memory leak issue
add the base class for KL methods
minor fix in CART and NEWS update
Merge pull request #2289 from mazumdarparijat/rf

minor fix in CART and NEWS update
added proper lapack check to address issue #2291
Merge pull request #2292 from lambday/develop

added proper lapack check to address issue #2291
Merge pull request #2286 from yorkerlin/variational-example

variational_approx_example using small dataset (for memory check)
Merge pull request #2287 from yorkerlin/develop

The base KL method class
prevent failure in class_list.cpp when LAPACK is not present
Merge pull request #2294 from lambday/develop

prevent failure in class_list.cpp when LAPACK is not present
modular API, bug fix for C4.5
refine lars and intro