Remove multi-threading capability.

[gmierz]

This capability was put in place in the hopes that it would speed things up, but the difference is not measurable. Either this needs to be removed all together, or replaced with multi-processing.

[gmierz]

So far, the logger has been changed to a single-process logger which also makes the output cleaner. The only thing left now is to remove the worker count arguments and remove the code which uses it.