Ascii Null not handled in print_string

[Yves Trudeau]

Just found cases where ascii nulls (\0) are in TEXT columns. The following change fix it

--- print_data.c.orig 2012-06-01 16:26:38.000000000 +0200
+++ print_data.c 2012-06-01 16:11:45.000000000 +0200
@@ -159,6 +159,7 @@
                else if (value[i] == '\n') out[out_pos++] = '\\', out[out_pos++] = 'n';
                else if (value[i] == '\r') out[out_pos++] = '\\', out[out_pos++] = 'r';
                else if (value[i] == '\t') out[out_pos++] = '\\', out[out_pos++] = 't';
+ else if (value[i] == '\0') out[out_pos++] = '\\', out[out_pos++] = '0';
        else {
             if (value[i] == ' ') {
                 num_spaces++;