Fix various minor problems and update the documentation (#237)

These are minor fixes I've accumulated over time. The following
changes are somewhat notable:

- Added a missing entry for 'typeset -s' to the man page.
- Add strftime(3) to the 'see also' section. This and the date(1)
  addition are meant to add onto the documentation for 'printf %T'.
- Removed the man page the entry for ksh reading $PWD/.profile on
  login. That feature was removed in commit aa7713c2.
- Added date(1) to the 'see also' section of the man page.
- Note that the 'hash' command can be used instead of 'alias -t' to
  workaround one of the caveats listed in the man page.
- Use an 'out of memory' error message rather than 'out of space'
  when memory allocation fails.
- Replaced backticks with quotes in some places for consistency.
- Added missing documentation for the %P date format.
- Added missing documentation for the printf %Q and %p formats
  (backported from ksh2020: https://github.com/att/ast/pull/1032).
- The comments that show each builtin's options have been updated.

src/cmd/ksh93/sh/array.c

@@ -1793,7 +1793,7 @@ void nv_setvec(register Namval_t *np,int append,register int argc,register char
 	{
 		ap = (struct index_array*)nv_arrayptr(np);
 		if(ap && is_associative(ap))
-			errormsg(SH_DICT,ERROR_exit(1),"cannot append index array to associative array %s",nv_name(np));
+			errormsg(SH_DICT,ERROR_exit(1),"cannot append indexed array to associative array %s",nv_name(np));
 	}
 	if(append)
 	{
@@ -1818,4 +1818,3 @@ void nv_setvec(register Namval_t *np,int append,register int argc,register char
 		nv_putval(np,argv[argc],0);
 	}
 }
-