Follows Dr Bainbridge's suggestion to prevent URL based calls to set-metadata and remove-meta metadataserver.pl operations. Split metadataaction.pm into modmetadataaction.pm and metadataaction.pm, shifting the methods that modify metadata (set and remove subroutines) into the first. Now GS3 sets an env var that will control whether the meta-modifying subroutines will be available when called. If the env var is set, then metadataaction.pm will include the modmetadataaction.pm file in the begin block. For GS2, it works as before, always including the meta modifying subroutines. Tested on Linux with the GS3 web doc editor vs calling metadataserver.pl to set metadata directly from a URL.
