Fix commands losing their trailing whitespace

Fixes issue 3901

Change-Id: Ic2293c067d7fa673dec9ce4a32127f87fe52c35f
Reviewed-on: http://gerrit.dmdirc.com/1040
Automatic-Compile: DMDirc Local Commits <dmdirc@googlemail.com>
Reviewed-by: Shane Mc Cormack <shane@dmdirc.com>

src/com/dmdirc/commandparser/CommandArguments.java

@@ -177,7 +177,7 @@ public class CommandArguments {
         Logger.assertTrue(start <= end + 1);
 
         final Pattern pattern = Pattern.compile("(\\S+\\s+){" + (start) + "}"
-                + "((\\S+\\s+){" + Math.max(0, end - start) + "}\\S+).*?");
+                + "((\\S+\\s+){" + Math.max(0, end - start) + "}\\S+(\\s+$)?).*?");
         final Matcher matcher = pattern.matcher(line);
 
         return matcher.matches() ? matcher.group(2) : "";