Checkpoint on calc version 2.12.8.0

Fixed a mistake in "help intro" where some inserted text
    changed the value of "." and thus made the next result
    incorrect.

    Clarified in "help factor" that 1 is returned if no
    factor below the limit was found.

    Removed Makefile variable ${MAKEFILE_REV}.

    The missing cscript/square.calc file has been restored.

    Fixed compiler errors and warnings related to GCC.
    In particular, gcc/9.3.1 and gcc/10.2.1 now compile
    calc without any compiler errors or warnings,
    even with -Werror -Wextra -pedantic.

    To print out information about the calc compliation
    environment, we added the following make rule:

	make calcinfo

    Improved how 'make debug' operates.

    Moved help/contrib to CONTRIB-CODE.  The help/contrib file
    is now build from a copy of CONTRIB-CODE.

    Created a new calc bug report Email address.  Created a new calc
    question Email address.  Created a new calc contribution Email
    address.  See the BUGS file for details.

    Added "help questions" to print the QUESIONS help file.

    If the environment variable $CALCHELP is defined and is non-empty,
    then calc help files will be in the direcgory by the $CALCHISTFILE
    environment variable.

    If the environment variable $CALCCUSTOMHELP is defined and is
    non-empty, then custom calc help files will be in the direcgory
    by the $CALCCUSTOMHELP environment variable.

    The calc-tester mailing list has been retired.  See:

	* How to submit a calc bug report:

	    http://www.isthe.com/chongo/tech/comp/calc/calc-bugrept.html

	* How to contribute code to calc:

	    http://www.isthe.com/chongo/tech/comp/calc/calc-contrib.html

	* How to submit a question about calc:

	    http://www.isthe.com/chongo/tech/comp/calc/calc-question.html

Makefile

@@ -8,7 +8,6 @@
 #	 comments, this Makefile differs from the non-rpm bzip2-ed tarball
 #	 source Makefile in the following ways:
 #
-#	 MAKEFILE_REV= $$Revision: 30.26 $$
 #	 CCWERR= -Werror
 #	 USE_READLINE= -DUSE_READLINE
 #	 READLINE_LIB= -lreadline -lhistory -lncurses
@@ -710,6 +709,9 @@ chk:
 #
 # debug
 #
+# make calcinfo:
+#       * print information about the host ane compile environment
+#
 # make env:
 #	* print major Makefile variables
 #
@@ -727,6 +729,11 @@ chk:
 #	* compile without optimizers to make debugging easier
 ##
 
+calcinfo:
+	${V} echo '=-=-=-=-= private Makefile $@ rule start =-=-=-=-='
+	${Q} ${MAKE} ${XARG} -f ${MAKE_FILE} $@ ${XVAR}
+	${V} echo '=-=-=-=-= private Makefile $@ rule end =-=-=-=-='
+
 env:
 	${V} echo '=-=-=-=-= private Makefile $@ rule start =-=-=-=-='
 	${Q} ${MAKE} ${XARG} -f ${MAKE_FILE} $@ ${XVAR}