Add option to not fill binary up to max address

[gzzi]

Hello,

In my scenario it make sense to not fill up to max address. The result binary is smaller and the update of our embedded device is then faster.

[eerimoq]

Please add a test and I'll merge =)

[eerimoq]

I guess you can remove everything from the end of the last segments end before calling as_binary() to achieve the same result. But I'm open to add the fill parameter.

[gzzi]

I found another way, I can call crop before doing the as_binary