1) Refactor the manpage to use the num-syntax and concise wording.
2) Build format instead of having a list of static strings.
3) BUGFIX: if (!buf[0] || buf[0] == '\n') Process last-read-line
properly.
4) BUGFIX: In case we hit a formatting line, print a newline instead
of just dropping it.
5) Use a switch instead of having spaghetti-cases.
6) Don't use printf-magic but explicitly do a putchar(' ')-loop.
7) Update usage(), indent properly.
8) BUGFIX: strchr is not NULL when type[0] is \0. Check for \0
separately beforehand.
9) Reorder arg.h-cases for better readability.
- add .Os, it is mandatory.
- don't redeclare .Nm when it's not needed.
- fix some warnings (checked with mandoc -Tlint).
- remove some leftover old stuff.
