Batch syntax / variant checker on LOVD.nl

[ifokkema]

Depends on #573.

Create an interface that:

• Works on the website. Since the LOVD.nl code is not (yet) versioned, either develop in LOVD's scripts folder or create a private LOVD.nl repository. Probably the former.
• Allows both syntax and variant validation, to be chosen by the user. Syntax check is fast, variant validation will be slower.
  • Syntax validation is always done first. When we have validated (and possibly improved) the syntax, the variant may also be sent to VV, which can in turn actually validate the variant itself. VV may also correct the description. Note that for variant validation, a reference sequence is required.
  • Hold off supporting LRGs or NGs right now, as VV doesn't support them well yet.
• Allows both for one-variant checks as well as a list of variants.
  • The list may be populated by copy/paste or the upload of a document.
• Results should be written to the screen, but should also become downloadable.
• Results should include;
  • The input
  • The corrected output
  • Whether there was a problem or not
  • Detailed error messages.
• It would be good to study the VV output format, so we can align our formats.
• Perhaps, due to time constraints, it would be good to first have the syntax checker working and online, and work on the rest after.