Big assertion capture refactoring.

- moved as much logic out of the macros as possible
- moved most logic into new ResultBuilder class, which wraps ExpressionResultBuilder (may take it over next), subsumes ResultAction and also takes place of ExpressionDecomposer.

This introduces many SRP violations - but all in the name of minimising macro logic!

include/internal/catch_legacy_reporter_adapter.hpp

@@ -46,7 +46,7 @@ namespace Catch
                     it != itEnd;
                     ++it ) {
                 if( it->type == ResultWas::Info ) {
-                    ExpressionResultBuilder expressionBuilder( it->type );
+                    ExpressionResultBuilder expressionBuilder( NULL, it->type );
                         expressionBuilder << it->message;
                     AssertionInfo info( it->macroName, it->lineInfo, "", ResultDisposition::Normal );
                     AssertionResult result = expressionBuilder.buildResult( info );