Deadwood snapshot update: execfile finished

OK, guys, I've decided to not devote any more time to execfile("foo") in Deadwood.

I have finished up the feature this morning; all files parsed with execfile must be in /etc/deadwood/execfile and errors in sub-files are not correctly reported; the workaround is Deadwood -f /etc/deadwood/execfile/filename, which will report the line a parse error is on.

I have also documented execfile.

The one last thing I will do before the next Deadwood 2.4 release is have it so, on Windows systems, execfile uses a different directory besides /etc/deadwood/execfile; probably just the same directory all the other Deadwood files are in Windows (#ifdef the chdir() to make sure it isn't used in Windows).

It's time to go back to merging multiple in-flight DNS requests.