test proxy supports CONNECT

There's a new 'http-proxy' server for tests that runs on a separate port
and lets clients do HTTP CONNECT to other ports on the same host to
allow us to test HTTP "tunneling" properly.

Test cases now have a <proxy> section in <verify> to check that the
proxy protocol part matches correctly.

Test case 80, 83, 95, 275, 503 and 1078 have been converted. Test 1316
was added.

tests/data/test1316

@@ -0,0 +1,62 @@
+<testcase>
+<info>
+<keywords>
+FTP
+PASV
+LIST
+HTTP CONNECT
+</keywords>
+</info>
+#
+# Server-side
+<reply>
+# When doing LIST, we get the default list output hard-coded in the test
+# FTP server
+<datacheck>
+HTTP/1.1 200 Mighty fine indeed
+
+HTTP/1.1 200 Mighty fine indeed
+
+total 20
+drwxr-xr-x   8 98       98           512 Oct 22 13:06 .
+drwxr-xr-x   8 98       98           512 Oct 22 13:06 ..
+drwxr-xr-x   2 98       98           512 May  2  1996 .NeXT
+-r--r--r--   1 0        1             35 Jul 16  1996 README
+lrwxrwxrwx   1 0        1              7 Dec  9  1999 bin -> usr/bin
+dr-xr-xr-x   2 0        1            512 Oct  1  1997 dev
+drwxrwxrwx   2 98       98           512 May 29 16:04 download.html
+dr-xr-xr-x   2 0        1            512 Nov 30  1995 etc
+drwxrwxrwx   2 98       1            512 Oct 30 14:33 pub
+dr-xr-xr-x   5 0        1            512 Oct  1  1997 usr
+</datacheck>
+</reply>
+
+#
+# Client-side
+<client>
+<server>
+ftp
+http-proxy
+</server>
+ <name>
+FTP LIST tunneled through HTTP proxy
+ </name>
+ <command>
+ftp://%HOSTIP:%FTPPORT/ -p -x %HOSTIP:%PROXYPORT
+</command>
+</client>
+
+#
+# Verify data after the test has been "shot"
+<verify>
+<protocol>
+USER anonymous
+PASS ftp@example.com
+PWD
+EPSV
+TYPE A
+LIST
+QUIT
+</protocol>
+</verify>
+</testcase>