Bug Fix - "done" tasks missing end date

- Tasks marked "done" were not assigned an end date before being
  written to the file.  Fortunately this only affects beta testers
  who, by definition, like to live on the edge.
- Added better text in the NEWS file regarding the github issue
  tracker.
- Cleaned up text a little in the "help" report output.

NEWS

@@ -33,7 +33,7 @@ order of increasing effort (to you) and usefulness (to me):
 
   - Another option involves using Github's issue tracker, which can be found
     at http://github.com/pbeckingham/task/issues which has the advantage that
-    everyone gets to see and track the issue.
+    everyone gets to see and track the issue.  You will still be a hero.
 
 Thank you.
 

src/command.cpp

@@ -603,7 +603,7 @@ std::string handleDone (TDB& tdb, T& task, Config& conf)
       // Add an end date.
       char entryTime[16];
       sprintf (entryTime, "%u", (unsigned int) time (NULL));
-      task.setAttribute ("end", entryTime);
+      seq->setAttribute ("end", entryTime);
 
       // Change status.
       seq->setStatus (T::completed);

src/task.cpp

@@ -222,11 +222,8 @@ static std::string shortUsage (Config& conf)
       << std::endl
       << "See http://www.beckingham.net/task.html for the latest releases and a "
       << "full tutorial.  New releases containing fixes and enhancements are "
-      << "made frequently."
+      << "made frequently.  Join in the discussion of task, present and future, "
-      << std::endl
+      << "at http://groups.google.com/group/taskprogram"
-      << std::endl
-      << "Join in the discussion of task, present and future, at "
-      << "http://groups.google.com/group/taskprogram"
       << std::endl
       << std::endl;