[ravedude] add output modes, newline after n bytes or after char

[tippfehlr]

From --help:

    -o <output-mode>
            Output mode. Can be ascii, hex, dec or bin

        --newline-on <newline-on>
            Print a newline after this byte
            not used with output_mode ascii
            hex (0x) and bin (0b) notations are supported.
            matching chars/bytes are NOT removed
            to add newlines after \n (in non-ascii mode), use \n, 0x0a or 0b00001010
        --newline-after <newline-after>
            Print a newline after n bytes
            not used with output_mode ascii
            defaults to 16 for hex and dec and 8 for bin
            if dividable by 4, bytes will be grouped to 4

This helps when working with non-ascii output.

Other solutions:

• use another serial console: too much context switching for me, having the serial console in watch mode is way better.
• use ravedude and pipe into hexdump or xxd: they only handle streamed data line by line, meaning the data is not printed immediately. They also can’t add newlines.

[Rahix]

Thanks a lot for your contribution! I like this change a lot.

Right now, we are doing a rather large rework of ravedude in #522. I'll get back to your PR once that work is finished, otherwise things will get a bit too messy. I don't expect a lot of conflicts with your changes, though.