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/lib/libast/include/ast.h

@@ -176,7 +176,7 @@ typedef struct
 #define FMT_ALWAYS	0x01		/* always quote			*/
 #define FMT_ESCAPED	0x02		/* already escaped		*/
 #define FMT_SHELL	0x04		/* escape $ ` too		*/
-#define FMT_WIDE	0x08		/* don't escape 8 bit chars	*/
+#define FMT_WIDE	0x08		/* don't escape 8-bit chars	*/
 #define FMT_PARAM	0x10		/* disable FMT_SHELL ${$( quote	*/
 
 /*