v2.0.0-rc3

• Improved Lateral Sparql Polyfill with support for concurrent and bulk requests.
• New concurrent SPARQL feature: Use SERVICE loop:concurrent+5-10:bulk+10: {}` for federation to the active dataset or a remote service.
  This example distributes the workload to 5 concurrent slots, each slot receiving 10 bindings and combining those 10 bindings into a single bulk request.
  The operator preserves the order of the input bindings to the SERVICE request.