Added named namelist templates and 'match' filter, fixed bugs and omissions

* Changed handling of '.use_template' to allow use of arbitrary template names
* Fixed error message for missing or wrong options
* Fixed setting ENVIRONMENT to 'DEFAULT' if set to empty in SETUP.config (see IssueID #5808)
* Added 'match' filter, allowing to use regular expression matches
* Added missing tests for 'wordwrap' filter
* Re-wrote documentation on additional Jinja filters