* Added text files with required module information, which can be used with pip.
* Added a batch file to build a ZIP archive with a standalone copy of the script, which can be used to run it under Windows systems without Python.
* Further tweaked the way the progress bar window works.
* Debug messages are no longer printed to the log.
* Rearranged some parts of the code.
* Use Python keywords in conditional blocks.
* Use one-liners whenever possible.
* Removed unused code.
* Only use a progress bar if the overall file size is greater than the hardcoded threshold value.
