DataSetToken implementation for NNLMs and related stuff.
$ . configure.sh
$ make && sudo make install
$ lua test/test.lua
<s> <s> => the
<s> the => u.s.
the u.s. => centers
u.s. centers => for
centers for => disease
for disease => control
disease control => and
control and => prevention
and prevention => in
prevention in => atlanta
...