Fixed a small bug in the DIE() error exit code.

Curses was not being properly shut down before displaying fatal error messages,
leaving the terminal in an undesirable state.
Added --linelength <n> / -l<n> command line option.

Adds a mechanism to explicitly specify the number of bytes to display per line.
I find that a lot of binary files that I look at have some sort of internal
alignment that makes them easier to visualize if each line contains a specific
number of bytes.
Merge pull request #2 from john-r-graham/master

add --linelength + bugfix exit code