Fix up and improve the linting functionality

[klauer]

Current Behavior

• whatrecord lint works on startup scripts and appears broken for database files at the moment
• Database instances contain .lint attributes tracking lint, which gets serialized along with everything else

Expected Behavior

I'd like linting to be pretty painless and something that can be readily used from whatrecord, with or without viewing from the frontend.

• whatrecord lint should work for database files, startup scripts, and other files
• It'd be nice if the lint was recorded in such a way that the frontend could view it as well
  • As-is, the lint is not stored at all, but regenerated on each call to the command-line tool
• The command-line tool should accept multiple input files

[klauer]

Of the things to work on in whatrecord, this one's higher up there.
Because:

• Linting is a particularly useful aspect of a parser that can handle a bunch of file types
• Linting of startup scripts and databases is a goal for our migration of IOCs to GitHub
• It needs cleaning because it's something I'd like collaborative efforts on; so the goal is to fix it prior to ICALEPCS or paper writing (if the conference attendance doesn't pan out)