Catch 'clipboard already open' errors in editors

Apparently following commits have not fixed the problem completely,
because it still happens (although not so often).

changeset: 2019:b8f795bdfe9f
user: Andrey Skvortsov <andrej.skvortzov@gmail.com>
date: Fri May 25 17:40:29 2018 +0300
summary: fix hangs on mouse selection in case if wxPython uses wxWidgets with GTK3+ support

changeset: 2018:5ce6d08ff2c7
user: Andrey Skvortsov <andrej.skvortzov@gmail.com>
date: Fri May 25 17:23:15 2018 +0300
summary: make clipboard open minimal time as wxPython documentation recommends

Project overview
================

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

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

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.

To be continued.