In chemfigit, added feature that uses newest .tex file in dest_dir
if tex_file is null (_chemfigit.py).
Also, log_level is now lowercase (_chemfigit.py & chemfigit.yml).
Updated doc for this new feature in chemfigit.yml.
Updated test/settings.yml to be consistent with latest -t template
output.
New version is 0.1.2.