Release 0.164.0

Changes to jsonpath:

• The values in the result_options bitmask have been changed from

  enum class result_options {value=1, path=2, nodups=4|path, sort=8|path}; (until 0.164.0)

to

enum class result_options {value=0, nodups=1, sort=2, path=4};            (since 0.164.0)

In practice this means that any combination of these values that includes
result_options::value has the same meaning as before, except that
result_options::value can now be omitted. And any combination that includes
result_options::path but not result_options::value has the
same meaning as before.

Enhancements to jsonpath:

• Functions now allow expressions to be passed as arguments, e.g.

  $.books[?(ceil(@.price*100) == 2272)]

• User provided custom functions are now supported

Changes to json_reader and csv_reader:

• The typedefs json_reader and wjson_reader have been deprecated,
  but for backwards compatibility they are still supported. They
  have been replaced by json_string_reader and wjson_string_reader
  for string sources, and json_stream_reader and wjson_stream_reader,
  for stream sources.

• The typedefs csv_reader and wcsv_reader have been deprecated,
  but for backwards compatibility they are still supported. They
  have been replaced by csv_string_reader and wcsv_string_reader
  for string sources, and csv_stream_reader and wcsv_stream_reader,
  for stream sources.