CRFsuite Ruby module via SWIG

* HOW TO BUILD

0. Build CRFsuite and install it (the library and include files are necessary)

1. Generate a SWIG wrapper
$ ./prepare.sh --swig

2. Build the binding.
$ ruby extconf.rb

3. Install the binding.
$ make install

4. Run the binding.
$ irb
irb(main):001:0> require 'crfsuite'


* SAMPLE PROGRAMS
Refer to sample_train.rb and sample_test.rb



* NOTES FOR INSTALLING CRFSUITE IN A NON-DEFAULT DIRECTORY

If you have changed the installation directory of CRFsuite using --prefix
option for the configure script, please specify the include and library
directories to setup.py; for example, if you have installed CRFsuite into
$HOME/local directory, run:

$ ruby extconf.rb --with-crfsuite-include=$HOME/local/include --with-crfsuite-lib=$HOME/local/lib