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!

projects/SelfTest/TrickyTests.cpp

@@ -318,19 +318,19 @@ TEST_CASE( "Assertions then sections", "[Tricky]" )
     // This was causing a failure due to the way the console reporter was handling
     // the current section
     
-    REQUIRE( Catch::isTrue( true ) );
+    REQUIRE( Catch::alwaysTrue() );
     
     SECTION( "A section", "" )
     {
-        REQUIRE( Catch::isTrue( true ) );
+        REQUIRE( Catch::alwaysTrue() );
         
         SECTION( "Another section", "" )
         {
-            REQUIRE( Catch::isTrue( true ) );
+            REQUIRE( Catch::alwaysTrue() );
         }
         SECTION( "Another other section", "" )
         {
-            REQUIRE( Catch::isTrue( true ) );
+            REQUIRE( Catch::alwaysTrue() );
         }
     }
 }