0.19.0

Added

• Support for custom fields. These fields allow you to run custom filter
  functions for anything that cannot be expressed with Flop filters.
• Added Flop.with_named_bindings/4 for dynamically adding bindings needed for
  a Flop query.
• Added fetch, get, get_all, delete, delete_first, drop, new,
  take, pop, pop_first, put and put_new functions to Flop.Filter.
• Added Flop.Meta.with_errors/3.
• Added ecto_type option to join fields.
• Added not_like and not_ilike filter operators.
• Added a cheatsheet for schema configuration.

Changed

• Renamed Flop.bindings/3 to Flop.named_bindings/3.
• Flop.Filter.allowed_operators/2 now tries to determine the Ecto type by
  reading the Flop field type from the schema module. This function is used
  during parameter validation, which means the validation step will be a bit
  stricter now. For join and custom fields, the Ecto type is determined via the
  new ecto_type option. If the option is not set, the function returns all
  operators as before. For compound fields, only the supported operators are
  returned.
• Added opts field to Flop.Meta struct.