Improve .RIS importer to not import incomplete references
This presumes a mechanism to validate a reference entry. A couple of criteria come to my mind:
A reference entry is considered to be valid for import when:
- The "Title" does not start with special characters, (such as when importing RIS from Endnote, "<")
- The reference entry must have at least a combiniation of values, e.g. a "Title" and an "Author" or "Publisher", etc.