Fix Pyro work with SSL wrapper (sslpsk)

Following error was shown in Beremiz console:
PYRO connecting to URI : PYROS://127.0.0.1:3001#beremiz
Exception while connecting to 'PYROS://127.0.0.1:3001#beremiz': non-zero flags not allowed in calls to recv() on <class 'ssl.SSLSocket'>
Connection failed to PYROS://127.0.0.1:3001#beremiz!

Reason is that Pyro calls socket recv() with MSGWAITALL flag, that causes ValueError exception.

https://docs.python.org/2/library/ssl.html
recv(), recv_into() (but passing a non-zero flags argument is not allowed)

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Project overview

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In order to target the widest possible range of programmable devices and keep efficient, Beremiz use C code as an intermediate language. 

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To be executed, C needs to be compiled. `GCC <http://gcc.gnu.org>`_ serve that purpose perfectly.

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PLC program is expressed in languages defined in IEC-61131, including graphical languages. Thanks to PLCopen TC2, those graphical languages have a standardised representation, in XML.

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To be continued.