basic/terminal-util: introduce SYSTEMD_COLORS environment variable ... to determine if color output should be enabled. If the variable is not set, fall back to using on_tty(). Also, rewrite existing code to use colors_enabled() where appropriate.

basic: include only what we use This is a cleaned up result of running iwyu but without forward declarations on src/basic.

tree-wide: sort includes in *.h This is a continuation of the previous include sort patch, which only sorted for .c files.

util-lib: move status printing stuff into src/core/ It's very specific to the core, and not used elsewhere, hence move it out of terminal-util.[ch].

machined: when opening a shell via machined, pass tty fds in With this change we'll open the shell's tty right from machined and then pass it to the transient unit we create. This way we make sure the pty is opened exactly as long as the transient service is around, and no longer, and vice versa. This way pty forwarders do not have to deal with EIO problems due to vhangup, as the pty is open all the time from the point we set things up to the point where the service goes away.

basic: move two more terminal-related calls into terminal-util.[ch]

logind: remove warn_melody() logic The internal speaker is usually not available on modern latops that support suspend, and even if it is available in the hardware, most distributions turned support for it off in the kernel. And even if it is enabled, it's probably still a bad idea to make use of it for the suspend-failures. If anything a proper sound should be played. Long story short, let's remove support of this anachronism.

cgtop: underline table header Let's underline the header line of the table shown by cgtop, how it is customary for tables. In order to do this, let's introduce new ANSI underline macros, and clean up the existing ones as side effect.

machined: introduce a ptsname_namespace() call and make use of it The call is like ptsname() but does not assume the pty path was accessible in the local namespace. It uses the same internal ioctl though.

build-sys: split internal basic/ library from shared/ basic/ can be used by everything cannot use anything outside of basic/ libsystemd/ can use basic/ cannot use shared/ shared/ can use libsystemd/