Add Hexiidump

Implemented `hexiidump` as shown by corkami:

https://corkami.googlecode.com/svn/trunk/src/HexII/.

Here's an example ![screenshot](https://corkami.googlecode.com/svn/trunk/src/HexII/HexII.png).
URL: https://corkami.googlecode.com/svn/trunk/src/HexII/HexII.png