Code Reorganization

- Added the ability for a command to specify it's own pirmary keyword.

src/commands/CmdExec.cpp

@@ -35,6 +35,7 @@ extern Context context;
 CmdExec::CmdExec ()
 : _external_command ("")
 {
+  _keyword     = "execute";
   _usage       = "task execute <external command>";
   _description = "Executes external commands and scripts";
   _read_only   = false;