fix and cleanup wildcard error msgs

* rename helper() into error_msg()
* clean logic to handle wildcard exceptions
* separate templates for html and text (CLI) modes also for das_ambiguous
* in das_wildcard_err, use same name 'msg' as in das_ambiguous for the error message
visual cleanup of generate_dasquery

* PEP8
* extract check_daskey(dasquery) which checks if given dasquery contain a valid daskey
remove unnecessary checks on DASQuery

* the parser already performs more complex checks, so this code is not needed
* renamed the error messages to make them more clear
Merge pull request #4090 from dmwm/wildcard_exc_kws_fix

fix and cleanup wildcard error msgs, refactor/cleanup generate_dasquery()