PS_open_file -- Opens a file for output
int PS_open_file(PSDoc *psdoc, const char *filename)
Creates a new file on disk and writes the PostScript document into
it. The file will be closed when PS_close(3) is called. If
filename is NULL, empty or `-', then the file
will be created in memory and retrieved with
Returns -1 in case of an error and 0 otherwise.