Make the 'history' and 'r' commands builtins (#76)

With this change no more preset aliases exist, so the preset alias
tables can be safely removed. All ksh commands can now be used
without 'unalias -a' removing them, even in interactive shells.
Additionally, the history and r commands are no longer limited to
being used in interactive shells.

src/cmd/ksh93/bltins/hist.c:
- Implement the history and r commands as builtins. Also guarantee
  lflag is set to one by avoiding 'lflag++'.

src/cmd/ksh93/Makefile,
src/cmd/ksh93/Mamfile,
src/cmd/ksh93/sh/main.c,
src/cmd/ksh93/sh/init.c,
src/cmd/ksh93/data/aliases.c:
- Remove the table of predefined aliases because the last few have
  been removed. During init the alias tree is now initialized the
  same way as the function tree.

src/cmd/ksh93/bltins/typeset.c:
- Remove the bugfix for unsetting predefined aliases because it is
  now a no-op. Aliases are no longer able to have the NV_NOFREE
  attribute.

src/cmd/ksh93/tests/alias.sh:
- Remove the regression test for unsetting predefined aliases since
  those no longer exist.

src/cmd/ksh93/data/builtins.c:
- Update sh_opthist[] for 'hist --man', etc.

src/cmd/ksh93/sh.1:
- Remove the list of preset aliases since those no longer exist.
- Document history and r as builtins instead of preset aliases.

Co-authored-by: Martijn Dekker <martijn@inlv.org>

src/cmd/ksh93/data/builtins.c

@@ -94,6 +94,8 @@ const struct shtable3 shtab_builtins[] =
 	"exit",		NV_BLTIN|BLT_ENV|BLT_SPC,	bltin(return),
 	"fc",		NV_BLTIN|BLT_ENV|BLT_EXIT,	bltin(hist),
 	"hist",		NV_BLTIN|BLT_ENV|BLT_EXIT,	bltin(hist),
+	"history",	NV_BLTIN|BLT_ENV|BLT_EXIT,	bltin(hist),
+	"r",		NV_BLTIN|BLT_ENV|BLT_EXIT,	bltin(hist),
 	"readonly",	NV_BLTIN|BLT_ENV|BLT_SPC|BLT_DCL,bltin(readonly),
 	"shift",	NV_BLTIN|BLT_ENV|BLT_SPC,	bltin(shift),
 	"trap",		NV_BLTIN|BLT_ENV|BLT_SPC,	bltin(trap),
@@ -953,11 +955,15 @@ const char sh_opthash[] =
 ;
 
 const char sh_opthist[]	= 
-"[-1cn?@(#)$Id: hist (AT&T Research) 2000-04-02 $\n]"
+"[-1cn?@(#)$Id: hist (AT&T Research/ksh93) 2020-07-16 $\n]"
 USAGE_LICENSE
-"[+NAME?\f?\f - process command history list]"
-"[+DESCRIPTION?\b\f?\f\b lists, edits, or re-executes, commands  "
+"[+NAME?fc, hist, history, r - process command history list]"
+"[+DESCRIPTION?\bhist\b lists, edits, or re-executes commands  "
 	"previously entered into the current shell environment.]"
+"[+?The following command equivalents exist: "
+	"\bfc\b is \bhist\b; "
+	"\bhistory\b is \bhist -l\b (list history); "
+	"and \br\b is \bhist -s\b (reexecute command).]"
 "[+?The command history list references commands by number. The first number "
 	"in the list is selected arbitrarily.  The relationship of a number "
 	"to its command does not change during a login session.  When the "
@@ -965,11 +971,11 @@ USAGE_LICENSE
 	"maintains the ordering.]"
 "[+?When commands are edited (when the \b-l\b option is not specified), the "
 	"resulting lines will be entered at the end of the history list and "
-	"then reexecuted by the current shell.  The \b\f?\f\b command that "
+	"then reexecuted by the current shell.  The \bhist\b command that "
 	"caused the editing will not be entered into the history list.  If the "
 	"editor returns a non-zero exit status, this will suppress the "
 	"entry into the history list and the command reexecution.  Command "
-	"line variable assignments and redirections affect both the \f?\f "
+	"line variable assignments and redirections affect both the \bhist\b "
 	"command and the commands that are reexecuted.]"
 "[+?\afirst\a and \alast\a define the range of commands. \afirst\a and "
 		"\alast\a can be one of the following:]{"