added a new kernel SSKStringKernel which implements the subsequence kernel (by lodhi et. al.). Also added to the modular interface
Added log_det method in CStatistics class
indentation fixed in Statistics.h
Fixed the previous messy commits
Unit test for log_det added. log_det updated.
Fixed doxygen info in log_det
Modified the unit test for log_det
Fixed indentation in Statistics.h
Merge pull request #956 from lambday/master

Added log_det method in CStatistics for Dense matrices