Expressions reboot

- Created A3.{h,cpp} which will be a simpler, lightweight version of
  Arguments.{h,cpp} that does less, but does it better.
- Created E9.{h,cpp} which will be a better implementation of
  Expression.{h,cpp} that does less, but does it better.
- Integrated A3 into Context::initialize, and Arguments and A3 will
  coexist until A3 surpasses Arguments.

src/Context.cpp

@@ -73,8 +73,8 @@ int Context::initialize (int argc, const char** argv)
   try
   {
     // char** argv --> std::vector <std::string> Context::args.
-    // TODO Handle "cal" case here.
     args.capture (argc, argv);
+    a3.capture (argc, argv);
 
     // echo one two -- three | task zero --> task zero one two
     // 'three' is left in the input buffer.
@@ -122,6 +122,9 @@ int Context::initialize (int argc, const char** argv)
     // Categorize all arguments one more time.  THIS IS NECESSARY.
     args.categorize ();
 
+    a3.categorize ();
+    a3.dump ("Initial");  // TODO Remove.
+
     // Handle default command and assumed 'info' command.
     args.inject_defaults ();
 
@@ -283,7 +286,7 @@ int Context::dispatch (std::string &out)
       tdb2.gc ();
     }
 
-    args.dump ("Argument Categorization");
+//    args.dump ("Argument Categorization");
     return c->execute (out);
   }
 
@@ -422,6 +425,17 @@ const std::vector <std::string> Context::getColumns () const
   return output;
 }
 
+////////////////////////////////////////////////////////////////////////////////
+const std::vector <std::string> Context::getCommands () const
+{
+  std::vector <std::string> output;
+  std::map <std::string, Command*>::const_iterator i;
+  for (i = commands.begin (); i != commands.end (); ++i)
+    output.push_back (i->first);
+
+  return output;
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 void Context::assumeLocations ()
 {