Added signal-based resolver timeout issue

 1.4 Get IP address

 1.5 c-ares ipv6

 1.6 configure-based info in public headers

 1.7 signal-based resolver timeouts

 2. libcurl - multi interface

 2.1 More non-blocking

 The remaining problems to solve involve the platforms that can't run

 configure.

1.7 signal-based resolver timeouts

 libcurl built without an asynchronous resolver library uses alarm() to time

 out DNS lookups. When a timeout occurs, this causes libcurl to jump from the

 signal handler back into the library with a sigsetjmp, which effectively 

 causes libcurl to continue running within the signal handler. This is

 non-portable and could cause problems on some platforms. A discussion on the

 problem is available at http://curl.haxx.se/mail/lib-2008-09/0197.html

 Also, alarm() provides timeout resolution only to the nearest second. alarm

 ought to be replaced by setitimer on systems that support it.

2. libcurl - multi interface

2.1 More non-blocking