* New overload of fail() specifies file and line
* BEAST_EXPECTS only evaluates the reason string on a failure
- This speeds up tests that call BEAST_EXPECTS
New overloads of suite::expect take the file and line number
as individual parameters, cleaning up the file name output
by showing only the filename part (to not leak the full path,
which might contain sensitive information).
A new macro BEAST_EXPECTS allows an additional reason
string as well as reporting the file and line. Typical usage:
```
error_code ec;
...
if(! BEAST_EXPECTS(! ec, ec.message()))
return;
```
The log member is changed to derive from std::ostream. A new
class dstream is derived from std::ostream to support redirection
to the Visual Studio Output Window if a debugger is attached.
Obsolete classes abstract_ostream and its derived variants are
removed.