Update Log:
2021.06.29
    - ffmpeg download link changes from 'essential' to 'full',
      full version is 128MB, so the download time is increased.
      !!! if you have issue with HAP codec, please update.
2021.03.05
    - update gif-maker to v4.0
      now support batching multiple file input.
2020.10.06
    - ffmpeg download link is updated again.
      using link from: https://www.gyan.dev/ffmpeg/builds/
      using 'essentials' instead of 'full' version of ffmpeg
2020.10.02
    - ffmpeg download link is updated.
2020.06.22
    - updated the download regex catcher for the installer.
      it was broken due to a change of the page layout on ffmpeg's website.
      I might remove the download code all together in the future version.
2020.06.02
    - a BUG in the code applying gamma 2.2 for exr input was fixed.
2020.05.16
    - add utility-muxer\concat script, a quick way to stitch multiple video clips together.
      this is a muxer script so no re-compression in the process.
    - add utility-muxer\add-audio script, you can add/ or replace audio to video(s).
      again this a muxer so the video codec is untouched.
2020.05.15
    - fixed a bug in video\prores script.
2020.05.09
    - script\utility-muxer\qTool-muxer-add-thumbnail.com is updated.
      it generates icon thumbnails for mp4 files. this is a muxer script,
      which means video's codec is un-changed, only meta-data is updated.
2020.05.06
    - fixed some small bugs in qbatch.cmd and video-downloader.cmd
      type 'qbath' in CMD to use the batch tool
      type 'youtube' in CMD to use video-downloader
2020.05.03
    - Updated the installer script.
2020.04.29 [v4]
    - This version is a major update.
      all the main scripts (image and video) scripts now support multiple input files.
      this means you can 'batch' a group of selected files all at once without using
      the batch script. see the user manual for more detail.
2020.04.11
    - rewrite the installer script. qTool can dynamically grab
      the latest version of command-line tools now.
2020.01.01
    - updated qTool_install.cmd, added backup option in menu.
    - updated web-video-download.cmd script with better menu system.
    - updated ffmpeg. All related scripts now support PSD file input.
2019.09.06
    - new gif-maker script support transparency gif export.