The feature is only enabled if the output is believed to be a tty.
-J: There's some minor differences and improvements in -J handling, as
now J should work with -i and it actually creates a file first using the
initial name and then *renames* that to the one found in
Content-Disposition (if any).
-i: only shows headers for HTTP transfers now (as documented).
Previously it would also show for pieces of the transfer that were HTTP
(for example when doing FTP over a HTTP proxy).
-i: now shows trailers as well. Previously they were not shown at all.
--libcurl: the CURLOPT_HEADER is no longer set, as the header output is
now done in the header callback.
Configuration files such as curl_config.h and all config-*.h no longer exist
nor are generated/copied into 'src' directory, now these only exist in 'lib'
directory from where curl tool sources uses them.
Additionally old src/setup.h has been refactored into src/tool_setup.h which
now pulls lib/setup.h
The possibility of a makefile needing an include path adjustment exists.
