This is a lot of stuff, and sometimes quite wild, let's turn this into
its own header.
All stuff color-related that just generates sequences is now in
ansi-color.h (no .c file!), and everything more complex that
probes/ineracts with terminals remains in termina-util.[ch]
Various of our tools operate on block devices, and it's not always
obvious to know which block devices are actually appropriate for use.
Hence, let's add a helper that allows to list block devices, and
supports some limited filtering.
Lennart Poettering