Updated Jamfile for compiling and linking against NPLM
    Added support for hierarchical maximum entropy LM through SRILM.

    Currently, the code compiles, but has not been run or tested.

    Steps to compile with maxent LM are below:

    - Download SRILM 1.6.0

    - Download the maxent patch from
      http://www.phon.ioc.ee/~tanela/srilm-me/srilm-1.6.0-me.patch

    - Download the required libLBFGS library from
      http://www.chokkan.org/software/liblbfgs

    - Edit SRILM's sbin/machine-type script
      to return MACHINE_TYPE=i686-m64 for case x86_64

    - Compile libLBFGS and install it in the /tools/SRILM/SRILM-1.7.0 directory.
      Make sure that the liblbfgs.* library files are in /tools/SRILM/SRILM-1.7.0/lib//

    - In the /tools/SRILM/SRILM-1.7.0 dir, apply the maxent patch to SRILM:
      patch -p1 < srilm-1.6.0-me.patch

    - Point the appropriate SRILM makefile
      to see libLBFGS's include and lib dirs, following the instructions at:
      http://www.phon.ioc.ee/dokuwiki/doku.php?id=people:tanel:srilm-me.en

    - Compile SRILM

    - Compile Moses using --with-srilm and --with-maxent-srilm:
      ./bjam --with-srilm=/tools/SRILM/SRILM-1.7.0 --with-maxent-srilm=true

    NOTE: The above steps were for my original integration.
          Current versions of SRILM (such as 1.7.1) include the maxent patch.
          As such, it should be sufficient to compile a current version of SRILM
          with support form maxent enabled,
          and then compile Moses using --with-srilm and --with-maxent-srilm:
          ./bjam --with-srilm=/tools/SRILM/SRILM-1.7.0 --with-maxent-srilm=true
Added comment in Jamroot on how to compile against NPLM
Re-enabled unit test for backward LM.

The test is compiling and running with no errors.