Fix a large number of typos and other problems (#110)

Most of these fixes are for typos and extra whitespace at the
end of lines. These are the notable changes:
- Fixed a compatibility issue with how asterisks are displayed
  using certain fonts. Bug report: https://github.com/att/ast/issues/764
- Fixed a bug in the man page that caused searches for the '|'
  character to fail. Bug report: https://github.com/att/ast/issues/871
- Removed a duplicate description of 'set -B' from the man
  page. Bug report: https://github.com/att/ast/issues/789
- Added documentation for options missing from the ksh man
  page (applies to 'hist -N', 'sleep -s', 'whence -q' and
  many of ulimit's options). Bug reports:
  https://github.com/att/ast/issues/948
  https://github.com/att/ast/issues/503#issuecomment-386649715
  https://github.com/att/ast/issues/507#issuecomment-507924608
- Applied the following ksh2020 documentation fixes:
  https://github.com/att/ast/pull/351
  https://github.com/att/ast/pull/352
- Fixed a minor GCC -Wformat warning in procopen.c by changing
  a sentinel to NULL.

src/lib/libast/man/getcwd.3

@@ -49,7 +49,7 @@ char* getcwd(char* \fIbuf\fP, size_t \fIlen\fP);
 .L getcwd
 copies the absolute path name of the current directory info into
 .I buf
-of length 
+of length
 .IR len .
 The return path may be longer than
 .LR PATH_MAX .
@@ -57,10 +57,10 @@ If
 .I "buff == 0"
 then space is allocated via
 .IR malloc (3)
-and 
+and
 .I len
 extra characters are reserved after the generated path name.
-A pointer to the path name is returned, 
+A pointer to the path name is returned,
 .L 0
 on error.
 .SH "SEE ALSO"