Add option to control dxf encoding.
Issue #863
new
DXF versions until R2007 (AC1021) are saved as ASCII files with the encoding set by the header variable $DWGCODEPAGE, which is ANSI_1252 by default if $DWGCODEPAGE is not set.
Right now, Valentina to export trying to guess encoding from current user language. This is not right in case if user opened pattern with text from different language. Such text will not be correctly converted.