Unified query api

[bmaranville]

In this PR

• the slddb query functions are consolidated to go through SLD_API.search(**opts)
• the functions to support webquery and blender are moved from the SLDDB codebase to here (orsopy.slddb)
• the SLD_API.localquery is refactored so it takes the same qdict argument as webquery
• SLD_API.use_webquery defaults to False
• SLD_API.update_db defaults to True
• this function then routes the request to either
  • a webquery to the SLDDB server (if api.use_webquery == True) or
  • a localquery, using the local copy of the db file

Default configuration

The combination of use_webquery=False and update_db=True means that, in the default configuration, this will happen:

• the first time a query is performed, the database age will be checked
• if it is older than max_age, a new copy is downloaded from the SLDDB server
• after that, all searches are local and use this refreshed copy of the database.

SLDDB-server independent configuration

If you set SLD_API.update_db = False before your first search (typically by doing orsopy.slddb.api.update_db = False), then no attempt is made to download a new copy of the database, and you use the version you currently have.

Webquery-preferred configuration

This is the currently the default in the released orsopy - orsopy.slddb.api.use_webquery = True, and it only falls back to the local db if the webquery fails. Every lookup then goes to the central SLDDB server.

[bmaranville]

The corresponding PR to remove the functions that were copied from SLDDB to here has not been made yet... in the SLDDB server code they'll be replaced by imports from here.

[aglavic]

Good idea to put this all in one place. I'd not remove the default webquery, though.

[aglavic]

Can't this be simply return sum(elements) ?

[aglavic]

I'd propose to do this simply by using a dictionary of collect functions and .get:

COLLECT_FUNCTIONS = {
  "protein": collect_protein,
  "dna": collect_dna,
  "rna": collect_rna,
  "db": collect_blendIDs,
}

[aglavic]

Making the default just a DB download will break the SLDdb statistical functions that are used to improve search results. (I.e. return most searched and most selected materials, first.)