First commit of (in progress) TeamCity reporter

Should run but is not complete

include/internal/catch_interfaces_reporter.h

@@ -238,6 +238,7 @@ namespace Catch
 
         virtual void assertionStarting( AssertionInfo const& assertionInfo ) = 0;
 
+        // The return value indicates if the messages buffer should be cleared:
         virtual bool assertionEnded( AssertionStats const& assertionStats ) = 0;
         virtual void sectionEnded( SectionStats const& sectionStats ) = 0;
         virtual void testCaseEnded( TestCaseStats const& testCaseStats ) = 0;