adstex v0.5.0

A new option --parallel (or -P for short) is introduced to enable parallel execution of adstex to speed things up. This new option is not enabled by default. When --parallel is set, adstex will use 8 threads to look up the references. One can adjust the number of threads by setting --threads=x.

Thanks to @dwijn for suggesting and implementing this new feature.

Full Changelog: v0.4.0...v0.5.0