0030694: Data Exchange - support non-standard GB2312-encoded STEP files

0030694: Data Exchange - support non-standard GB2312-encoded STEP files

STEPCAFControl_Reader::SourceCodePage() - added property defining text encoding
for converting names within STEPCAFControl_Reader::ReadNames() method.
Added associated "read.stepcaf.codepage" parameter,
which default value is Resource_UTF8, preserving current behavior.

Resource_FormatType enumeration has been extended by UTF8 and SystemLocale values.
Resource_Unicode - added conversion methods taking Resource_FormatType as argument.

GetName command has been corrected to NOT replace non-Latin symbols.