document prompt in shell script mode, fix man formatting, legacy awk

Documented unexpected behavior when calc is running in
"shell script mode" and the prompt builtin function is used
without the -p flag.  Updated help/prompt, help/unexpected
and the calc man page accordingly.

Unless calc is given the -p command line option, calc will reopen
stdin as /dev/null instead of just closing stdin.  This prevents
subsequent opens grabbing the 1st file descriptor.

Disable regress tests 4709, 4710, and 7763 because they print
multi-byte sequences, which are just fine for calc, the awk
used to evaluate the regression suite output in some legacy
systems report a "multibyte conversion failure".

Added a number of missing Makefile variables to the "make env" rule.

The man command is used to format the calc.1 man page into calc.usage.

The "help calc" command now prints the formatted calc man page (calc.usage).
The "help man" command now prints the formatted calc man page (calc.usage).
The "help usage" command now prints the formatted calc man page (calc.usage).

The file, calc.cat1, is formed by gzipping the calc.usage
formatted man page.  The calc.cat1 is installed as the calc
cat section 1 man page.

Updated the Copyright string in version.c to refer to
the COPYING file and the "help copying" command.

Added calc.cat1 to .gitignore.  Using "sort -d -u" to sort .gitignore content.

Avoiding use of modern [[ and ]] in Makefile for those legacy systems
whose shell do not support them.  *sigh*

Fixed the order of "help full" to match the order of topics listed
buy the "help help" command.

Sorted the halias[] help topics table in help.c using sort -d -u.

Makefile.config

@@ -997,9 +997,6 @@ endif	# ($(target),Darwin)
 #
 # Use CATDIR= to disable installation of the calc cat (formatted) page.
 #
-# NOTE: If CATDIR is non-empty, then one should have either the
-#	${NROFF} executable and/or the ${MANMAKE} executable.
-#
 CATDIR=
 #CATDIR= ${PREFIX}/man/cat1
 #CATDIR= ${PREFIX}/catman/cat1
@@ -1026,36 +1023,6 @@ CATEXT= 1
 #CATEXT= 0
 #CATEXT= l
 
-# how to format a man page
-#
-# If CATDIR is non-empty, then
-#
-#     If NROFF is non-empty, then
-#
-#	  ${NROFF} ${NROFF_ARG} calc.1 > ${CATDIR}/calc.${CATEXT}
-#		   is used to build and install the cat page
-#
-#     else (NROFF is empty)
-#
-#	  ${MANMAKE} calc.1 ${CATDIR}
-#		     is used to build and install the cat page
-# else
-#
-#     The cat page is not built or installed
-#
-# If in doubt and you don't want to fool with man pages, set MANDIR
-# and CATDIR to empty and ignore the NROFF, NROFF_ARG and MANMAKE
-# lines below.
-#
-#NROFF= nroff
-NROFF=
-#NROFF= groff
-NROFF_ARG= -man
-#NROFF_ARG= -mandoc
-MANMAKE= ${PREFIX}/bin/manmake
-#MANMAKE= manmake
-MANMODE= 0444
-CATMODE= 0444
 
 # By default, custom builtin functions may only be executed if calc
 # is given the -C option.  This is because custom builtin functions
@@ -1296,13 +1263,13 @@ CAT= cat
 CHMOD= chmod
 CMP= cmp
 CO= co
-COL= col
 CP= cp
 CTAGS= ctags
 DATE= date
 DIFF= diff
 FMT= fmt
 GREP= grep
+GZIP= gzip
 HOSTNAME= hostname
 LANG= C
 LDCONFIG= ldconfig
@@ -1310,6 +1277,7 @@ LN= ln
 LS= ls
 MAKE= make
 MAKEDEPEND= makedepend
+MAN= man
 MKDIR= mkdir
 MV= mv
 PWDCMD= pwd
@@ -1321,8 +1289,8 @@ SORT= sort
 SPLINT= splint
 SPLINT_OPTS=
 STRIP= strip
-TEE= tee
 TAIL= tail
+TEE= tee
 TOUCH= touch
 TRUE= true
 UNAME= uname