Handle dig failure

Test using Dynu.com as well as Duckdns.org

Issue #614: Fix delimiter issues with ${alldomains[]} in create_csr()

Wrong SANS when domain contains a minus character

A regexp to extract 'Subject Alternative Name' doesn't work when the domain use a minus character.

For grep regexp, to lose its special meaning inside brackets, the minus character must be placed in the first or last position in the list.

https://www.gnu.org/software/grep/manual/grep.html#Character-Classes-and-Bracket-Expressions

- use \n as delimiter for read to array
- use \n as delimiter for comparing SANs

mktemp not working correctly on Alpine Linux (added XXXXXX to template)

Fixes #612

Release v2.31

Fix bug with nslookup server param

Fix indentation to two spaces in other_scripts/cpanel_cert_upload

Follow EditorConfig, use consistent space indent in Nginx test configs

Correct Makefile indentation in .editorconfig

Add "Table of Contents" in README.md

Make markdownlint happy about README.md

```
README.md:1 MD041/first-line-heading/first-line-h1 First line in file should be a top level heading [Context: "![Run all tests](https://githu..."]
README.md:2 MD022/blanks-around-headings/blanks-around-headers Headings should be surrounded by blank lines [Expected: 1; Actual: 0; Above] [Context: "# getssl"]
```

Remove deprecated Travis CI config

Improve README.md code block readability by correct syntax highlight

Looks like getssl was not using Travis CI for a while:
https://travis-ci.org/github/srvrco/getssl

And the GitHub Actions was introduced for a while:
https://github.com/srvrco/getssl/commits/master/.github/workflows

Remove Travis CI config in the repository will help contributor reduce
the confusion about which CI platform is currently using.

Wildcard support in ACMEv2 - fixes #347 and #400

Fixes #347 and #400