Add shared library for parsing stream format

[mr-martian]

This is relevant to apertium/apertium#213 and probably other things

[mr-martian]

Tests pass, though I haven't applied it to any real data yet

[unhammer]

seems like tests in nno-nob pass with it (I built&installed lttoolbox and apertium with --prefix=$HOME/PREFIX/lttoolbox and did export PATH=$HOME/PREFIX/lttoolbox/bin:$PATH && cd apertium-nno-nob && make -j test)

[unhammer]

Was there a reason for not merging this yet?

I just tried this with nob-nno on a corpus, no diffs on 2k lines.

[unhammer]

After installing lttoolbox and apertium to $HOME/PREFIX/lttoolbox, I tried

$ cat test/fra-oci*input.txt | apertium fra-oci >/tmp/old && cat test/oci-fra*input.txt | apertium oci-fra >>/tmp/old;

$ export LD_LIBRARY_PATH=$HOME/PREFIX/lttoolbox/lib

$ export PATH=$HOME/PREFIX/lttoolbox/bin:$PATH

$ cat test/fra-oci*input.txt | apertium -d /usr/share/apertium/ fra-oci >/tmp/new && cat test/oci-fra*input.txt | apertium -d /usr/share/apertium/ oci-fra >>/tmp/new
# (lots of stderr this time)

$ diff -s /tmp/{old,new}
Files /tmp/old and /tmp/new are identical

When I comment out the stderr stuff, speed seems the same as well.