Reported by the new script 'scripts/copyright.pl'. The script has a
regex whitelist for the files that don't need copyright headers.

Removed three (mostly usesless) README files from docs/

Closes #5141

As has been outlined in the DEPRECATE.md document, the axTLS code has
been disabled for 6 months and is hereby removed.

Use a better supported TLS library!

Assisted-by: Daniel Gustafsson
Closes #3194

- replace tabs with spaces where possible
- remove line ending spaces
- remove double/triple newlines at EOF
- fix a non-UTF-8 character
- cleanup a few indentations/line continuations
  in manual examples

Closes https://github.com/curl/curl/pull/3037

- also update two URLs outside of docs/examples
- fix spelling of filename persistant.c
- fix three long lines that started failing checksrc.pl

Closes https://github.com/curl/curl/pull/3036

Detected using the `codespell` tool (version 1.13.0).

Also secure and fix an URL.

Closes #1356

We're mostly saying just "curl" in lower case these days so here's a big
cleanup to adapt to this reality. A few instances are left as the
project could still formally be considered called cURL.

closes #371

- update default versions of dependencies (except for rare/old platforms)
- update urls
- sync examples makefiles with main ones
- remove line ending space