Tags beginning with a non alpha-numeric character are now disallowed.

Added !throws special tag which denotes a test case to be skipped when run with -e
(the idea being that the test case is expected to throw an exception which is not caught within a XXX_THROWS assertion).

include/internal/catch_console_colour.hpp

@@ -58,7 +58,7 @@ namespace Catch {
         static void use( Code _colourCode );
 
     private:
-        static Detail::IColourImpl* impl;
+        static Detail::IColourImpl* impl();
     };
 
 } // end namespace Catch