* Empty strings are now direct constructed as `std::string()`, not as empty string literals.
* `startsWith` and `endsWith` no longer construct new a string. This should be an improvement
for libstdc++ when using older standards, as it doesn't use SSO but COW and thus even short
strings are expensive to first create.
* Various places now use char literal instead of string literals containing single char.
** `startsWith` and `endsWith` now also have overload that takes single char.
Generally the performance improvements under VS2015 are small, as going from short string
to char is mostly meaningless because of SSO (Catch doesn't push string handling that hard)
and previous commit removed most string handling if tests pass, which is the expect case.
Catch passes ::tolower into std::transform with string iterators.
::tolower has the signature int(int), which triggers a stealth narrowing
warning inside std::transform, because transform calls
*_Dest = _Fn(*_First), which implicitly narrows an int to a char.
For this particular application the narrowing is fine, so explicitly
narrow in a lambda.
- 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!
