Don't use streaming features for simple SGMatrix/SGVector i/o

Instead use their load routines. Require splitted up 7 class data
example (into data and labels) and adjust news accordingly. Drop
unnecessary includes in examples (don't!)
seed random number generator
revert commit 001790288e12ada4bd2d4956007b4f87834d84c7 for main Makefile
make examples fail nicely when eigen3 is not available
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
Removed SSKStringKernel
Added doxygen info of log_det method in CStatistics
Merge branch 'master' of https://github.com/lambday/shogun