Move "make pem" to "./unrealircd makecert" and make tools use this

and refer to this as well.

Suggested by PeGaSuS in https://bugs.unrealircd.org/view.php?id=6610

This also moves extras/tls.cnf to doc/conf/tls/tls.cnf which
also gets installed in ~/unrealircd/conf/tls/ (or whatever CONFDIR is)

And just to be clear: this means you can run "./unrealircd makecert"
without needing to go into BUILDDIR (or even having it at all).

At the same time, the generation commands have been modified slightly
so two warnings during certificate generation are no longer there.

Config

@@ -188,7 +188,7 @@ if [ "$QUICK" != "1" ] ; then
 			echo "*******************************************************************************"
 			echo "Press ENTER to continue"
 			read cc
-			$MAKE pem
+			./unrealircd makecert
 			echo "Certificate created successfully."
 			sleep 1
 		else