Make the write() method more tolerant of a script that is in the process

of being terminated (e.g. user hitting Ctrl-C in jsexec) - don't open
and truncate the .cnf file if we're going to exit with an exception
anyway and likely leave a 0-byte .cnf file behind.

exec/load/cnflib.js

@@ -231,6 +231,8 @@ var CNF = new (function() {
 					return false;
 			}
 		}
+		if(js.terminated)
+			return false;
 		var f = new File(fullpath(fileName));
 		if(!f.open('wb'))
 			return false;
@@ -242,4 +244,4 @@ var CNF = new (function() {
 
 })();
 
-CNF;
\ No newline at end of file
+CNF;