Remove sys/sys/scanio.h.

sys/sys/scanio.h was left behind when ss(4) was removed in 1db263f4.
Revive games.

requested by drahn@, jcv@ and oga@
ok pedro@
Add HISTORY section and more information regarding AUTHORS.
Feedback and ok Eric Allman (via Kirk McKusick, thanks!), ok jmc@ sobrado@.
In preparation for getline and getdelim additions to libc, rename getline()
occurrences to get_line().
Based on a diff from Jan Klemkow <j-dot-klemkow-at-wemelug-dot-de> to tech.
typos
Teach rain(6) to calculate terminal delays in the same way as worms(6),
rather than use a default which totally floods the network if run over ssh.

Discussed with matthieu@ martynas@, ok matthieu@
Update for new -d default; tweaks+ok jmc@
Use an en-dash for 20-200, escape - used as arithmetic symbol.
Same as jmc's tweaks for rain(6).
make both -d options format the same, and zap that annoying full stop
typo; netbsd -r1.10
two spelling fixes; from John-Mark Gurney (freebsd -r243048);
pjanzen spotted that my previous commit mistakenly omitted another
spelling fix;
grammar fix; from Chris Petrik, freebsd pr 173868
Remove excessive sys/cdefs.h inclusion
ok guenther millert kettenis
macro fixes;
typo; fix from patrick keshishian
typo fix; from pgoyette, netbsd -r1.15 and -r1.11, respectively;
this doesn't need to be time_t ok deraadt
teenagers from *outer* space ("they blast the flesh off hunmans!");
Correct obviously exchanged labels in the "computer warpcost" output and
fix a typo in a comment; from <Ted dot Roby at gmail dot com> on tech@.