Added wrapper makefile to optionally include common makefiles of
frameworks triggering the compilation process.
Modernized autotools.
Updated author's email address.
Completed last commit.
Fixed vio::io::readable and vio::io::writable.

Both methods now longer invoke callback functions in case of
vio::io::reusable or vio::io::unusable.

Added vio::io::set::hop to skip current event if a callback
function decided to delete the instance the event is pointing to.
Marked vio::io::set_p to be thread_local.

Still uncommented until next stable Debian.
Marked vio::uds/tcp::subs to be thread_local.

Still uncommented until next stable Debian.
Added explicit check for readability.

This is required if we got what we wanted to read. In this case
we do not know if we are still readable or if we just emptied the
buffer. So we assume to be not readable and reinitalize the epoll
event handler. This way we ge notified again if there still was
data, which is generally not the case with edge-triggering.
Removed previous added readability check.

This check was already there. When the previous get() invokation
emptied the buffer, the next one would get EAGAIN. The problem
here was that it invoked the callback function with an argument
done of 0. That might invoke a following user call of put() with
a size of 0, too. And that resulted into a false positive check
of a closed connection. This check only makes sence within
readable() and thus was removed from writable(). Nevertheless, now
it would also result into a false positive check for general
errors. The solution is to just prevent a callback function to be
called without progress. This check was added for readable() and
writable().
Implemented auto-hopping when dropping.

Made add()/mod()/del() non-static.
Removed resetting of io_p within run().

Saves one CPU cycle within main loop.