CONNECT to a proxy with digest

it works, as it has proved to not work in some cases (like on Tor Arntsen's
AIX 5100-06 xlc 5.0 --disable-shared runs).

for diff output get created in the log/ dir and no longer deletes them since
they help in understanding the problem, fixing the test case and fixing curl
problems.

on lots of perl versions, provide our own base64 decoder

(http://qa.mandrakesoft.com/show_bug.cgi?id=12285), when connecting to an
IPv6 host with FTP, --disable-epsv (or --disable-eprt) effectively disables
the ability to transfer a file. Now, when connected to an FTP server with
IPv6, these FTP commands can't be disabled even if asked to with the
available libcurl options.

that!

with binary data.

clash with djgpp ioctl() macro in setup.h.

(http://qa.mandrakesoft.com/show_bug.cgi?id=12289), curl would print a newline
to "finish" the progress meter after each redirect and not only after a
completed transfer.

If EPSV, EPRT or LPRT is tried and doesn't work, it will not be retried on
the same server again even if a following request is made using a persistent
connection.

If a second request is made to a server, requesting a file from the same
directory as the previous request operated on, libcurl will no longer make
that long series of CWD commands just to end up on the same spot. Note that
this is only for *exactly* the same dir. There is still room for improvements
to optimize the CWD-sending when the dirs are only slightly different.

Added test 210, 211 and 212 to verify these changes. Had to improve the
test script too and added a new primitive to the test file format.