fixed some AC_SUBST configure entries.

- Bug report #1792649 (http://curl.haxx.se/bug/view.cgi?id=1792649) pointed
  out a problem with doing an empty upload over FTP on a re-used connection.
  I added test case 541 to reproduce it and to verify the fix.

- I noticed while writing test 541 that the FTP code wrongly did a CWD on the
  second transfer as it didn't store and remember the "" path from the
  previous transfer so it would instead CWD to the entry path as stored. This
  worked, but did a superfluous command. Thus, test case 541 now also verifies
  this fix.

case 615 to test an SFTP upload failure.

and allow reuse by multiple protocols. Several unused error codes were
removed.  In all cases, macros were added to preserve source (and binary)
compatibility with the old names.  These macros are subject to removal at
a future date, but probably not before 2009.  An application can be
tested to see if it is using any obsolete code by compiling it with the
CURL_NO_OLDIES macro defined.

Documented some newer error codes in libcurl-error(3)

out that libcurl didn't deal with large responses from server commands, when
the single response was consisting of multiple lines but of a total size of
16KB or more. Dan Fandrich improved the ftp test script and provided test
case 1006 to repeat the problem, and I fixed the code to make sure this new
test case runs fine.

out that doing first a file:// upload and then an FTP upload crashed libcurl
or at best caused furious valgrind complaints. Fixed now by making sure we
free and clear the file-specific struct properly when done with it.

out that libcurl didn't deal with very long (>16K) FTP server response lines
properly. Starting now, libcurl will chop them off (thus the client app will
not get the full line) but survive and deal with them fine otherwise. Test
case 1003 was added to verify this.

download transfer size much earlier to be possible to get read with
CURLINFO_CONTENT_LENGTH_DOWNLOAD as soon as possible.

  (http://curl.haxx.se/bug/view.cgi?id=1776232) about libcurl calling
  Curl_client_write(), passing on a const string that the caller may not
  modify and yet it does (on some platforms).

(http://curl.haxx.se/bug/view.cgi?id=1776235) about ftp requests with NOBODY
on a directory would do a "SIZE (null)" request. This is now fixed and test
case 1000 was added to verify.

HTTP PUT using Digest authentication. Test case 5320 and 5322 were also
added to verify the functionality.

NTLMFLAG_NEGOTIATE_UNICODE, we need to filter it off because libcurl doesn't
unicode encode the strings it packs into the NTLM authenticate packet.

size earlier when doing HTTP downloads, so that applications and the
progress meter etc know get the info earlier in the flow than before.

the configure script checks for openldap and friends and we link with those
libs just like we link all other third party libraries, and we no longer
dlopen() those libraries. Our private header file lib/ldap.h was renamed to
lib/curl_ldap.h due to this. I set a tag in CVS (curl-7_17_0-preldapfix)
just before this commit, just in case.

countermeasures code path.

(http://curl.haxx.se/bug/view.cgi?id=1766320) pointing out that the libcurl
code accessed two curl_easy_setopt() options (CURLOPT_DNS_CACHE_TIMEOUT and
CURLOPT_DNS_USE_GLOBAL_CACHE) as ints even though they're documented to be
passed in as longs, and that makes a difference on 64 bit architectures.

after 7.16.2. This is much due to the different treatment file:// gets
internally, but now I added test 231 to make it less likely to happen again
without us noticing!

passed to it with curl_easy_setopt()! Previously it has always just refered
to the data, forcing the user to keep the data around until libcurl is done
with it. That is now history and libcurl will instead clone the given
strings and keep private copies.

NTLM, and he provided test code and a test server and we worked out a bug
fix. We failed to count sent body data at times, which then caused internal
confusions when libcurl tried to send the rest of the data in order to
maintain the same connection alive.

(and then I did some minor reformatting of code in lib/http.c)

of a socket after it has been closed, when the FTP-SSL data connection is taken
down.

support for the OS/400 Secure Sockets Layer library

some few internal identifiers to avoid conflicts, which could be useful on
other platforms.