Made shared_strings_XML a string, workbook is Marshal-able
Made shared_strings_XML a string, workbook is Marshal-able

ryanmark/rubyXL,99cm/rubyXL,99cm/rubyXL,ryanmark/rubyXL,mezza/rubyXL,parallel588/rubyXL,weshatheleopard/rubyXL,mezza/rubyXL,weshatheleopard/rubyXL,ThijsWouters/rubyXL,parallel588/rubyXL,99cm/rubyXL,weshatheleopard/rubyXL,mezza/rubyXL,ThijsWouters/rubyXL,parallel588/rubyXL,ryanmark/rubyXL