setup libsvm format interface for load- and saving.
add TestCase for LibSVM dataset parsing and writing.
add first version for parsing libsvm dataset files.
use finer floatpoint literal for checking value literals in libsvm format.
add implementation for LibSVM::save
add prefered_feature argument to libSVM::load methods for
guaranteing a minimal dataset matrix size.
add documentation for OpenANN::LibSVM parsing and converting methods.
Change LibSVM implementation to column-major order (current OpenANN
standard for DirectStorageDataSets)
Merge branch 'libsvm' of https://github.com/Ruun/OpenANN into Ruun-libsvm

Conflicts:
	test/test.cpp