Changes an extended attribute. \n
* The data will be internally duplicated. \n
* If data is NULL the attribute is removed.
* If data_type is BYTE then count can be -1 to indicate a NULL terminated string.
* See also \ref imDataType.
*
* \verbatim ifile:SetAttribute(attrib: string, data_type: number, data: table of numbers or string) [in Lua 5] \endverbatim
* If data_type is IM_BYTE, as_string can be used as data.
* \ingroup file
Changes an extended attribute. \n * The data will be internally duplicated. \n * If data is NULL the attribute is removed. * If data_type is BYTE then count can be -1 to indicate a NULL terminated string. * See also \ref imDataType. * * \verbatim ifile:SetAttribute(attrib: string, data_type: number, data: table of numbers or string) [in Lua 5] \endverbatim * If data_type is IM_BYTE, as_string can be used as data. * \ingroup file