issue2551147 - Enable compression of http responses in roundup. gzip, (brotli/zstd with optional packages) on the fly compression/content-encoding enabled by default. Can serve pre-compressed static assets as well if the client can accept it. Docs updated. Also added example nginx config to installation.txt. The config allows nginx to compress data on the fly. If the config is used, dynamic compression in roundup can be disabled. Dedicating this checkin to my father Paul Hector Rouillard 1930-2021. I did much of the development in this changeset while sitting with him as he slept/transitioned. Without his encouragement and example, my desire to learn would not be what it is and I wouldn't be half the person I am.

Debugging Aids
--------------

Try turning on logging of DEBUG level messages. This may be done a number
of ways, depending on what it is you're testing:

1. If you're testing the database unit tests, then set the environment
   variable ``LOGGING_LEVEL=DEBUG``. This may be done like so:

    LOGGING_LEVEL=DEBUG python -m pytest test/

   This variable replaces the older HYPERDBDEBUG environment var.

2. If you're testing a particular tracker, then set the logging level in
   your tracker's ``config.ini``.

SENDMAILDEBUG
=============

Set to a filename and roundup will write each email message
that it sends to that file instead to the internet. 
This environment variable is independent of the python -O flag.