Encode symbols in zone names for REST API URLs
API: create SOA records with complete content

No surprises when editing an existing SOA, then.
Catch conversion error and ignore it for logging
make sure we don't exceed the number of available filedescriptors for mthreads. You can still overshoot a little bit, but not all mthreads will be using an fd.
_actually_ raise the limit to the max if impossible to fit within the hard limit
avoid merging old and new additional data, fixes an issue caused by weird Akamai behaviour
Coverity nits

Should fix CID 1168020, 1167490, 1167489, 1167488, 1126082.
Merge pull request #1269 from zeha/coverity

Coverity nits in webserver code
Merge pull request #1267 from cmouse/fix-remotebackend-unittest-http

Catch conversion error and ignore it for logging
Merge pull request #1264 from zeha/ws-mangle-zone-id

Encode symbols in zone names for REST API URLs
Merge pull request #1265 from zeha/ws-full-soa-data

API: create SOA records with complete content
Comment out empty else clauses
Fix narrowing issue
Styled as per request