The previous output was read correctly by LyX as well, but the new version is
more similar to the files written by LyX. Also update TODO with recent file
format changes.
It is invoked by 'make check' (automake only, it would be nice if someone
could add it to cmake as well), or by calling
python src/tex2lyx/test/runtests.py <path to tex2lyx binary>
by hand. Currently, it does not compare the output (this comes later).
The added .lyx files are from tex2lyx around mid of april, so that you
can see the regressions of the current version if you run the test
yourself (simply run git diff afterwards).
The home made test runner is quite stupid, but better than nothing.
Feel free to improve it or replace it with something better, as long
as running it stays as simple as now.