Address prefix optional offset and variable width support

[matcap]

Using the library I found the need to print address prefixes starting from a pre-determined offset instead of 0,
so I added display_offset field to HexConfig (defaults to 0).

Before:

0000:   00 c3 50 01  ce ed 66 66   ..P...ff
0008:   cc 0d 00 0b  03 73 00 83   .....s..

With display_offset set to 0x0100:

0100:   00 c3 50 01  ce ed 66 66   ..P...ff
0108:   cc 0d 00 0b  03 73 00 83   .....s..

As a consequence, since now addresses can be greater than 0xff, I added support for automatically displaying addresses with larger width.

With display_offset set to 0x010000:

010000:   00 c3 50 01  ce ed 66 66   ..P...ff
010008:   cc 0d 00 0b  03 73 00 83   .....s..

With display_offset set to 0x10000000:

10000000:   00 c3 50 01  ce ed 66 66   ..P...ff
10000008:   cc 0d 00 0b  03 73 00 83   .....s..

[wolandr]

Looks good, thank you

[Sharpiro]

this looks great, any idea when a new release will be cut?