Avoid usage of localized strings before initialization during import in many modules

This happens if import is done before i18n setup
(InstallLocalRessources()).
This affects PLCOpenEditor mostly. Beremiz IDE is free from this issue, but moving
initialization from import should make modules more robust.
Otherwise execution result depends on where and when import was done
and this is not a good thing.

Some modules (ConfigTreeNode, features, CodeFileEditor related
classes) still have this, but they are used only in Beremiz.
Most problems result in non-working internatialization.
In some cases (VariablePanel) there is backtrace, because localized
key is not found in non-localized dictionary.

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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.