e621dl 5.10.0

Option to not redownload deleted files, new Cloudflare captcha support, NSFW by default and lots of bugfixes

• Cloudflare changed it's captcha to something more
  profitable and more irritating. Since there is no way
  to solve it without Javascript, I can't use my old trick.
  So, instead we solve it in browser in Incognito, but
  we change browser's User-Agent and copy cookies to
  e621dl after we did so

• Detailed instruction for how to solve Cloudflare
  was made, replacing an obsolete one

• New settings option, no_redownload, applied to all
  configs if it's set to true in at least one of them.
  blocks deleted files from being redownloaded.

• Default rating changed to all possible, NSFW included.
  Because honestly, that's what this tool is for.

• During experiments with http headers, new allowed
  compression method was discovered, brotli, and looks like
  e621.net uses it by default. So, to use it, new
  dependency, brotli, are now required
  pip install brotli if you use source code version

• In README.md install instruction was updated.

• Now dictionary of all unique images is created once
  per run, not once per config again. Partial downloads
  are appended to the dict as well as to old_files table.

• Databases are created even if they were deleted after
  e621dl closing during active run. This leads to undefined
  behavior of pruning is used, but at least it will not
  prevent e621dl from running.

• Image regular expression fixed so partial downloads are
  not count. Bug happened when partial downloads were count
  as images in filedict.

• Partial downloads not checked if there is a copy in the
  same folder or if it's in a filedict. Copied directly
  if there is.

• Some minor bugfixes