Query method in Reader class

[lukavdplas]

Each Reader object should have a query method that allows a (rudimentary) search through the catalogus.

For example, we might support the following queries:

• minimum / maximum date
• search for keywords in:
  • the author or publisher
  • any bibliographical field, or any biographical field
  • any metadata

Note that this may include and/or logic.

It probably makes sense if we makes sense to decide on a JSON representation of the query here, which will ultimately be generated by the EDPOP frontend.

[jgonggrijp]

Note that this may include and/or logic.

I suggest not in a way that the user can control (let alone nest), though. Either all query parameters are ORed, or they are all ANDed. I suspect the latter would be less surprising to the user, but I can be easily convinced otherwise.