Build

- Enabled compiler warnings, which were off.  Yikes.
- Fixed all compiler warnings on OSX.

src/commands/CmdExec.cpp

@@ -39,7 +39,7 @@ CmdExec::CmdExec ()
 }
 
 ////////////////////////////////////////////////////////////////////////////////
-int CmdExec::execute (const std::string& command_line, std::string& output)
+int CmdExec::execute (const std::string& command_line, std::string&)
 {
   return system (command_line.c_str ());
 }