Issues downloading software from THe HDF Group Support site

Users have reported issues downloading software from The HDF Group Support site.
There are several issues that we are aware of:

1. Browser issue with "tar.gz" files:

   There is an issue on some browsers with downloading and uncompressing "tar.gz" files from
   The HDF Group web site. In cases where this has occurred, the md5 checksum of the downloaded
   file does not match the checksum for the file on our web site.

   Following is an example of downloading the HDF5-1.8 source code with the latest version of Firefox.
   The md5 checksum for the file that was downloaded is:

      $ md5sum hdf5-1.8.20.tar.gz
      37512e3a5bf3e42f811141d39df2b643 hdf5-1.8.20.tar.gz

   The checksum of the original file on our web site is:

      7f2d3fd67106968eb45d133f5a22150f hdf5-1.8.20.tar.gz

   The file cannot be uncompressed in one step:

      $ gzip -cd hdf5-1.8.20.tar.gz | tar xvf -
      tar: Archive is compressed. Use -z option
      tar: Error is not recoverable: exiting now

   However, it can be uncompressed in two steps:

      $ gzip -d xxx.tar.gz
      $ tar xvf xxx.tar

   We have encountered this issue with Firefox and Internet Explorer, but not with Google Chrome
   or wget.

2. Unsupported protocol error when using "curl" (Fixed):

   The HDF Group web site now properly redirects HTTP URLs. The redirection was broken, which
   caused a problem when using curl. Curl does not rewrite HTTP URLS when encountering the HSTS
   (HTTP Strict Transport Security) policy.

3. Checksum error when installing with "Homebrew" on MacOS:

   A checksum error has been reported when building hdf5 from source on MacOS using Homebrew.
   The szip formula, which is a dependency of the hdf5 formula, contains an error. An issue is
   being prepared to correct the szip formula with Homebrew.

   The following is an example of the error that occurs:

     $ brew install --build-from-source szip hdf5
     Downloading ftp://ftp.hdfgroup.org/lib-external/szip/2.1.1/src/szip-2.1.1.tar.gz
     ######################################################################## 100.0%
     Error: SHA256 mismatch
     Expected: 897dda94e1d4bf88c91adeaad88c07b468b18eaf2d6125c47acac57e540904a9
     Actual: 21ee958b4f2d4be2c9cabfa5e1a94877043609ce86fde5f286f105f7ff84d412
     Archive: /Users/SomeUser/Library/Caches/Homebrew/szip-2.1.1.tar.gz
     To retry an incomplete download, remove the file above.

   Recent 3rd party commits to the szip Homebrew formula have changed the source url and checksum in error.

   When the formula has been repaired at Homebrew, users experiencing this issue should:

    - Remove any cached packages for szip at: /Users/SomeUser/Library/Caches/Homebrew/szip-2.1.1.tar.gz
    - Update the szip brew formula: "brew upgrade <formula>"
    - Repeat the build from the source install command.

   More information about using homebrew can be found at:

      https://docs.brew.sh/FAQ.html

   The Cakebrew gui utility may also be helpful to diagnose Homebrew issues, install packages
   and keep the Homebrew software and formulas up-to-date. See:

      https://www.cakebrew.com/