fix many compilation warnings about static variables used by non-static functions

[CC] plc_main.c -> plc_main.o
/tmp/be/build/plc_main.c:396:40: warning: ?LogBuff? is static but used in inline function ?copy_from_log? which is not static
memcpy((char*)buf + remaining, LogBuff[level], size - remaining);
^
/tmp/be/build/plc_main.c:395:22: warning: ?LogBuff? is static but used in inline function ?copy_from_log? which is not static
memcpy(buf, &LogBuff[level][buffpos], remaining);
^
...

^
/tmp/be/build/plc_debugger.c:825:20: warning: ?retain_offset? is static but used in inline function ?BufferIterator? which is not static
Retain(retain_offset, size, real_value_p);
^
/tmp/be/build/plc_debugger.c:823:47: warning: ?retain_offset? is static but used in inline function ?BufferIterator? which is not static
unsigned int next_retain_offset = retain_offset + size;
^
^

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IEC 61131-3

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===========

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    IEC-61131 is a normative document provided by the standards organization IEC

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    (International Electrotechnical Commission) and describing a standard for

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    implementing programmable controllers.

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    The part 3 of this document (commonly named IEC 61131-3) specifies syntax and 

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    semantics for programming language for programmable controllers. Beremiz

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    implements all the languages described in this document. 

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    http://www.iec.eu

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PLCopen TC6

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===========

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    PLCopen is a vendor- and product-independent worldwide association defining

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    international standards for various topics related to control programming.

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    For this purpose, PLCopen has 6 technical committees.

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    The goal of the sixth committee (TC6) is to define a standard file format, 

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    based on XML, for exchanging programmables controllers programmed using 

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    IEC 61131-3 languages. Beremiz uses this file format for saving the PLC

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    programs of projects.

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    http://www.plcopen.org

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