Ensure correctness of metadata for library papers

[dipamsen]

Often, library papers have duplicate papers, wrongly labeled papers, and/or unparseable metadata in papers. To resolve these issues as much as possible, the following changes are needed:

Admin Dashboard

• Add button to edit Similar Papers, or easily 'compare' (and edit) metadata and content of two similar papers
• Option to replace papers (Replace Paper Feature #113), may require deletion of library papers
• Add warning before allowing approval if similar (approved) paper exists

The one case which is not handled by the above changes, is non conflicting wrong metadata papers (wrong course code, wrong exam/sem/yr, without conflicting paper having same metadata).

[dipamsen]

Also, could be useful to mark papers as being from library vs uploaded, in the admin approval page

[harshkhandeparkar]

I think the first part of this issue is relevant here. We can probably start with that one.