Add D_EXTEND (#885) (thanks to @ad8-bdl!)

* fix get-zones code block indentation

* extend D_EXTEND to handle subdomains

* fix targets: make absolute incl. subdomain where necessary

* clarify subdomain target test (not IP && not fqdn)

* Add parse_tests for D and D_EXTEND

* _getDomainObject: examine all domains

* human readable form

* consistent test IP addresses

* Improve docs and formatting

* propagate subdomain to canonicalisation

* en-US spelling

* rm extraneous console.log

* ignore subdomain for CF_REDIRECT

* clarify D_EXTEND doc re. CF_REDIRECT

* rm extraneous linebreak

* _getDomainObject: examine all domains

* human readable form

* consistent test IP addresses

* propagate subdomain to canonicalisation

* en-US spelling

* rm extraneous console.log

* ignore subdomain for CF_REDIRECT

* clarify D_EXTEND doc re. CF_REDIRECT

* rm extraneous linebreak

* GANDI_V5: Use github.com/go-gandi/go-gandi, not github.com/tiramiseb/go-gandi (#883)

* DOCUMENTATION: Fix error in CNAME.md (#877)

The current example `CNAME("def", "test.subdomain"), // def.example.com -> test.subdomain.example.com` is invalid (correctly raises a validation error, "ERROR: in CNAME def.example.com: target (test.subdomain) must end with a (.)")

* typos, fmt; example syntax fixes and real output

* formatting; re-add lost comment

* RecordConfig subdomain should be nullable

* providers/cscglobal/api.go: Fix fmt string

* More tests and docs

* go generate

Co-authored-by: Ben L <47653825+ad8-bdl@users.noreply.github.com>

providers/cscglobal/api.go

@@ -158,7 +158,7 @@ func (c *api) get(endpoint string) ([]byte, error) {
 
 	if resp.StatusCode == 400 {
 		// 400, error message is in the body as plain text
-		return nil, fmt.Errorf("CSC Global API error: %w URL: %s%s",
+		return nil, fmt.Errorf("CSC Global API error: %s URL: %s%s",
 			bodyString,
 			req.Host, req.URL.RequestURI())
 	}