pw-mon: add support for colored output

Same CLI as pw-dump, i.e. -N, --no-colors, --color=always etc are
supported.

This uses a for-loop macro hack to automatically print prefixes and
suffixes, the with_prefix() macro resolves into the correct printf
statements to insert either just the marker "*" or the ansi sequences
for color/reset. Use of the macro is simply:
```
   with_prefix(true, stderr) {
	fprintf(stderr, "this will be prefixed\n");
   }
```

man/pw-mon.1.rst.in

@@ -33,6 +33,10 @@ OPTIONS
 --version
   Show version information.
 
+-N | --color=WHEN
+  Whether to use color, one of 'never', 'always', or 'auto'. The
+  default is 'auto'. **-N** is equivalent to **--color=never**.
+
 AUTHORS
 =======