Incorporate libsvm-java-kernel for native tree kernel development

cleartk-ml-tksvmlight is nice but it is still somewhat annoying because if I 
want to do research on tree kernel methods I would have to modify the 
svmlight-tk source (in c) for doing the training then duplicate the changes in 
java in the cleartk library for test time. Unfortunately, libsvm, which has 
java and cleartk bindings, is not written very generally and it's hard to do 
tree kernels with it (there is something called customized kernel which I've 
tried and it was very inefficient).

Recently I found this nice package:
https://github.com/syeedibnfaiz/libsvm-java-kernel
which re-packages libsvm with some simple modifications that make it easy to 
extend kernel functions to structured instances like trees. The author says he 
emailed the libsvm people about using his changes and they did not respond to 
him.

Anyways, my point is it might be nice to have something like this in cleartk. 
Probably the best way to proceed is to upload the libsvm-java-kernel package to 
maven central, then create a cleartk-ml-libsvm-kernel module which uses it for 
doing native tree kernel development.  It will be independent of the 
cleartk-ml-libsvm module so that that module can follow latest libsvm and this 
module can lag a bit if necessary to allow time for libsvm-java-kernel to 
upgrade.

Original issue reported on code.google.com by tim.mil...@gmail.com on 12 Jun 2013 at 7:51

JamesHe1990 / cleartk

Incorporate libsvm-java-kernel for native tree kernel development #376