mingw32 fixes

Fixed test_last_endpoint (#80)

Reverted cleanups of copyrghts

Optimize atomics implementaiton for the Tile architecture

For atomic_counter and atomic_ptr classes, detect the Tile architecture
using #if defined __tile__ matching ARM and Solaris and then use the
Tile atomic instructions. Without this change, the default Mutex
implementation is used, which is slower.

Work around for LIBZMQ-496

The problem is that other threads might still be in mailbox::send() when
it is destroyed. So as a workaround, we just acquire the mutex in the
destructor. Therefore the running send will finish before the mailbox is
destroyed.

See also the fix for LIBZMQ-281 in zeromq2-x.
Signed-off-by: Mika Fischer <mika.fischer@zoopnet.de>

Update PGM with recent changes

Fixed CMake building after encoder/decoder changes

Fixed copyrights in sources

* Starting draft ZMTP/2.1 protocol (revision 2)
* Basis for adding security to the wire protocol
* Maintains backward compatibility

Copyrights had become ads for Sustrik's corporate sponsors, going against the original
agreement to share copyrights with the community (that agreement was: one line stating
iMatix copyright + one reference to AUTHORS file). The proliferation of corporate ads
is also unfair to the many individual authors. I've removed ALL corporate title from
the source files so the copyright statements can now be centralized in AUTHORS and
source files can be properly updated on an annual basis.

Adapted zmq_socket_monitor man page to new API.

Changed message structure for event notifications

Simplified zmq_event_t structure.

Simplified the zmq_event_t structure for easier access and better usability towards language bindings.

Fixed Linux compilation problem

remote_thr.cpp: port pthreads usage to win32 api

this follows what {local,remote}_lat.cpp and inproc_{thr,lat}.cpp do.

Windows: Fix rounding error in now_us. [Jira LIBZMQ-514]

Improve accuracy of time calculations and avoid division by zero when
ticksPerSecond.QuadPart < 1000000.