add selected byte information

[rbran]

This add a section that display the current byte selected information into multiple formats:

TODO list:

• [x] Include byte information.
• [x] Update byte information based selected byte on main screen.
• [ ] Update byte information based selected byte on the Hex View.
• [ ] Draw a indicator to what byte is selected

[sharkdp]

Very cool! Thank you for your contribution.

I'll wait with my review until you have resolved your own to-do list, unless you think this should be integrated in the current state.

[rbran]

I'm unable to find an elegant solution for the missing two objectives, the current implementation uses 100% of CPU. I'll study the gui lib better and search for a better solution once I get more time.