Struct related to range faceting query.

Example

iex> x = %Hui.Query.FacetRange{range: "year", gap: "+10YEARS", start: 1700, end: 1799}
%Hui.Query.FacetRange{
  end: 1799,
  gap: "+10YEARS",
  hardend: nil,
  include: nil,
  method: nil,
  other: nil,
  per_field: false,
  range: "year",
  start: 1700
}
iex> y = %Hui.Query.Facet{range: x, field: ["type", "year"], query: "year:[2000 TO NOW]"}
%Hui.Query.Facet{
  contains: nil,
  "contains.ignoreCase": nil,
  "enum.cache.minDf": nil,
  excludeTerms: nil,
  exists: nil,
  facet: true,
  field: ["type", "year"],
  interval: nil,
  limit: nil,
  matches: nil,
  method: nil,
  mincount: nil,
  missing: nil,
  offset: nil,
  "overrequest.count": nil,
  "overrequest.ratio": nil,
  pivot: nil,
  "pivot.mincount": nil,
  prefix: nil,
  query: "year:[2000 TO NOW]",
  range: %Hui.Query.FacetRange{
    end: 1799,
    gap: "+10YEARS",
    hardend: nil,
    include: nil,
    method: nil,
    other: nil,
    per_field: false,
    range: "year",
    start: 1700
  },
  sort: nil,
  threads: nil
}
iex> y |> Hui.Encoder.encode # render struct into URL query string with `facet` prefixes
"facet=true&facet.field=type&facet.field=year&facet.query=year%3A%5B2000+TO+NOW%5D&facet.range.end=1799&facet.range.gap=%2B10YEARS&facet.range=year&facet.range.start=1700"

Example - per field ranges, f.[fieldname].facet.range

iex> x = %Hui.Query.FacetRange{range: "year", gap: "+10YEARS", start: 1700, end: 1799, per_field: true}
%Hui.Query.FacetRange{
  end: 1799,
  gap: "+10YEARS",
  hardend: nil,
  include: nil,
  method: nil,
  other: nil,
  per_field: true,
  range: "year",
  start: 1700
}
iex> x |> Hui.Encoder.encode
"f.year.facet.range.end=1799&f.year.facet.range.gap=%2B10YEARS&facet.range=year&f.year.facet.range.start=1700"
# another range
iex> y = %Hui.Query.FacetRange{range: "price", gap: "10", start: 0, end: 100, per_field: true} 
%Hui.Query.FacetRange{
  end: 100,
  gap: "10",
  hardend: nil,
  include: nil,
  method: nil,
  other: nil,
  per_field: true,
  range: "price",
  start: 0
}
iex> z = %Hui.Query.Facet{field: "type", range: [x, y]} # field and multiple ranges faceting
%Hui.Query.Facet{
  contains: nil,
  "contains.ignoreCase": nil,
  "enum.cache.minDf": nil,
  excludeTerms: nil,
  exists: nil,
  facet: true,
  field: "type",
  interval: nil,
  limit: nil,
  matches: nil,
  method: nil,
  mincount: nil,
  missing: nil,
  offset: nil,
  "overrequest.count": nil,
  "overrequest.ratio": nil,
  pivot: nil,
  "pivot.mincount": nil,
  prefix: nil,
  query: nil,
  range: [
    %Hui.Query.FacetRange{
      end: 1799,
      gap: "+10YEARS",
      hardend: nil,
      include: nil,
      method: nil,
      other: nil,
      per_field: true,
      range: "year",
      start: 1700
    },
    %Hui.Query.FacetRange{
      end: 100,
      gap: "10",
      hardend: nil,
      include: nil,
      method: nil,
      other: nil,
      per_field: true,
      range: "price",
      start: 0
    }
  ],
  sort: nil,
  threads: nil
}
iex> z |> Hui.Encoder.encode
"facet=true&facet.field=type&f.year.facet.range.end=1799&f.year.facet.range.gap=%2B10YEARS&facet.range=year&f.year.facet.range.start=1700&f.price.facet.range.end=100&f.price.facet.range.gap=10&facet.range=price&f.price.facet.range.start=0"