Bug 445 - The command 'task h' should be ambiguous, yet works

- Fixed bug #445, which caused task to not notice that the command 'h' is
  ambiguous.  This was caused by mistakenly first autoCompleting against
  a set of alias names, during canonicalization, instead of autoCompleting
  against the whole set of possible commands and aliases, then doing the
  canonicalization.  The order was reversed.
- Also populated list of all commands with alias names, so the above
  could be corrected.

src/command.cpp

@@ -475,10 +475,6 @@ int handleCompletionCommands (std::string &outs)
   std::vector <std::string> commands;
   context.cmd.allCommands (commands);
 
-  // Concatenate a list of all aliases.
-  foreach (name, context.aliases)
-    commands.push_back (name->first);
-
   // Sort alphabetically.
   std::sort (commands.begin (), commands.end ());