Avoid unhandled Poller exceptions

The changes allow the Poller to avoid provoking unhandled NullReference
or ObjectDisposed exceptions when its attached sockets are closed
improperly. In runtime, these result in irrecoverable crashes. An
alternative to the fixes is to perform sanity checks in the
Socket.Close() method and throw exceptions accordingly.
Merge pull request #143 from KyleRudy/master

Avoid unhandled Poller exceptions
Update README.md
Update README.md
Allow XSUB/XPUB to send/recv messages unrelated to sub/unsub

Messages not prefixed with 0 or 1 can be send from subscriber to
publisher.
Merge pull request #145 from sofusmortensen/master

Allow XSUB/XPUB to send/recv messages unrelated to sub/unsub
ported stream engine fix from ZeroMQ (0c0a351fa5ffed3b66206eac6b77cef2fb316151
Signaler using ephemeral port
Update README.md

Fixed spelling error (stanands => standards) in Contributing section.
Corrected name of case style for methods (CamelCase => PascalCase). -- The first letter in the identifier and the first letter of each subsequent concatenated word are capitalized. You can use Pascal case for identifiers of three or more characters.
Merge pull request #149 from JayShelton/patch-1

Update README.md
Fix NetMQ msg and memory management to be the same as ZeroMQ, preparing for BufferPool
Msg byte array is from BufferPool
re-organize the socket send / recieve methods
hopefully a fix to the two timers bug that always fails
Merge pull request #146 from somdoron/StreamEngineFix

ported stream engine fix from ZeroMQ
merge with latest zeromq master
Merge pull request #147 from somdoron/MonoFix

Signaler using ephemeral port
Merge pull request #150 from somdoron/ZeroMemory

Zero memory and Buffer Pool