Bug#672361: bootlogd: escape sequences should be filtered out

[Jesse Smith]

> Please, don't. Issue with '\r' can be resolved by removal of '\r' in
> `bin:lsb-base'.

Okay, I'll do an option for completely unfiltered and other tools and be
adjusted to match.

> With filtering as implemented now `/var/boot/log' looks bad both in editor
> and terminal. Example:
>
>   Fri Feb 22 18:42:36 2019: [....] Not activating swap on logical volume. ...??7[warn8?? (warning).
>   Fri Feb 20 18:42:36 2019: [....] Starting early crypto disks...sda3_crypt (running)...??7[ ok 8??done.
>

For situations like this where you already have a log with escape
characters in it, you can fix the output by using the readbootlog
program, which is part of the sysvinit suite. It cleans out most of the
control characters so the log looks like a normal, plain-text file.