add some mandoc pages and fix some warnings

- 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.

grep.1

@@ -1,10 +1,11 @@
 .Dd November 21, 2014
 .Dt GREP 1 sbase\-VERSION
+.Os
 .Sh NAME
 .Nm grep
 .Nd search files for patterns
 .Sh SYNOPSIS
-.Nm grep
+.Nm
 .Op Fl EFHchilnqsvx
 .Op Fl e Ar pattern
 .Op Fl f Ar file
@@ -56,8 +57,8 @@ Print nothing, only return status.
 Suppress the error messages ordinarily written for nonexistent or unreadable files.
 .It Fl v
 Select lines which do
-.B not
-Match the pattern.
+.Sy not
+match the pattern.
 .It Fl w
 The expression is searched for as a word (as if surrounded by '\<' and '\>').
 .It Fl x