Fixed a bug in the custom unit testing framework which was throwing away any exceptions being thrown by the tests (thanks to Paul Kirth for finding this and reporting it). Fixing this bug revealed that enumerate() with a glob on Windows has never worked properly and the exception thrown by MSVC's checked iterators was hiding the problem, so fixed that bug too.

Added async_io_dispatcher_base::post_op_filter() and async_io_dispatcher_base::post_readwrite_filter(), including documentation examples and integrating filters into the unit testing. post_readwrite_filter() ought to be particularly useful to those seeking deep ASIO integration. Thanks to Bjorn Reese for the long discussions leading up to this choice of improved ASIO support.
Fixed tabs.
Refreshed AFIO benchmarks for v1.2.

Added build benchmarks.