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/cmd/ksh93/sh/name.c

@@ -3522,7 +3522,7 @@ void nv_setref(register Namval_t *np, Dt_t *hp, int flags)
 
 /*
  * get the scope corresponding to <index>
- * whence uses the same values as lseeek()
+ * whence uses the same values as lseek()
  */
 Shscope_t *sh_getscope(int index, int whence)
 {

src/cmd/ksh93/sh/xec.c

@@ -3024,7 +3024,7 @@ Sfdouble_t sh_mathfun(Shell_t *shp,void *fp, int nargs, Sfdouble_t *arg)
 /*
  * This routine is used to execute the given function <fun> in a new scope
  * If <fun> is NULL, then arg points to a structure containing a pointer
- *  to a function that will be executed in the current environment.
+ * to a function that will be executed in the current environment.
  */
 int sh_funscope(int argn, char *argv[],int(*fun)(void*),void *arg,int execflg)
 {