Fixes in 1998/schweikh2

There were a number of problems in the README.md that were fixed. A big
one was in usage where it said you could run the program and then input
a number. Although one could certainly go through that action it would
have no effect. Not entering a number at the command line does something
different (in a way different) from specifying a number.

Also the historical notes were updated to be more consistent and
hopefully clearer than before.

Since the author called the program yarng (see README.md for why this
is) the Makefile now creates a symlink to it, rather than forcing users
to go back and forth as the author gives example uses as well. The to
use and try sections now also use yarng. Running make clobber (from make
clean) will remove the symlink.

The .gitignore file was updated: added yarng.

The thanks-for-fixes.md file was updated slightly for the above changes,
particularly the historical remarks, linking indeed to the historical
remarks in the README.md file.

1998/schweikh2/Makefile

@@ -38,7 +38,7 @@ include ../../var.mk
 
 # Common C compiler warnings to silence
 #
-CSILENCE= -Wno-trigraphs -Wno-sign-compare -Wno-string-plus-int -Wno-switch-bool
+CSILENCE= -Wno-trigraphs -Wno-sign-compare -Wno-string-plus-int -Wno-switch-bool -Wno-implicit-int
 
 # Common C compiler warning flags
 #
@@ -132,15 +132,13 @@ all: data ${TARGET}
 
 ${PROG}: ${PROG}.c
 	${CC} ${CFLAGS} $< -o $@ ${LDFLAGS}
+	${LN} -sf $@ yarng
 
 # alternative executable
 #
 alt: data ${ALT_TARGET}
 	@${TRUE}
 
-${PROG}.alt: ${PROG}.alt.c
-	${CC} ${CFLAGS} $< -o $@ ${LDFLAGS}
-
 # data files
 #
 data: ${DATA}
@@ -157,7 +155,7 @@ everything: all alt
 ###############
 #
 clean:
-	${RM} -f ${OBJ} ${ALT_OBJ}
+	${RM} -f ${OBJ} ${ALT_OBJ} yarng
 	@-if [ -f indent.c ]; then \
 	    echo ${RM} -f indent.c; \
 	    ${RM} -f indent.c; \