Add trailing line with data length

[Glutexo]

Some hex dumping utilities add one more line. It contains only the first offset part with the actual length of the data. Like this:

000003f0  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000400  00 00 00 00                                       |................|
00000404

It is helpful as it can be immediately seen how long the data is without needing to count the actually present bytes on the last line of the dump.

Just adding here as a suggestion.