Some Clara/ command line clean-up and tweaks

include/catch_runner.hpp

@@ -150,11 +150,12 @@ namespace Catch {
                 m_config.reset();
             }
             catch( std::exception& ex ) {
-                std::cerr   << "\nError in input:\n"
-                            << Text( ex.what(), TextAttributes()
-                                                    .setInitialIndent(2)
-                                                    .setIndent(4) )
-                            << "\n\n";
+                {
+                    Colour colourGuard( Colour::Red );
+                    std::cerr   << "\nError in input:\n"
+                                << Text( ex.what(), TextAttributes().setIndent(2) )
+                                << "\n\n";
+                }
                 m_cli.usage( std::cout, m_configData.processName );
                 return (std::numeric_limits<int>::max)();
             }