move some rules into 1337.mk

A number of rules have been moved from entry `Makefile`s into the
`1337.mk` include file to make it easier for these common rules to be
updated or modified globally (by modifying the `1337.mk` include file).

The entry level `Makefile`s are now similar in form to the
/Makefile.example](https://github.com/ioccc-src/mkiocccentry/blob/master/Makefile.example)
file from the other repo.

The following make rules were moved into the `1337.mk` include file:

- `make indent.c`
- `make install`
- `make diff_orig_prog`
- `make diff_prog_orig`
- `make diff_alt_prog`
- `make diff_prog_alt`

This simplifies the entry level `Makefile`s so that they mostly reflect
the specifics of the particular entry.

Mentioned in FAQ 4.2, that the make diff rules are in the `1337.mk` include file.

Fixed invalid TAB character in `faq.md`.

Removed `make clean` directives that removed `indent.c`.  This file is now
removed via `make indent_clean`, a clean rule that also removes `indent.c`.

Removed `make clobber` directives that removed sandwich,  This file is now
removed via `make indent_clobber`, a clean rule that also removes `sandwich`.

Added `make indent_clean` and `make indent_clobber` rules into the top level
`Makefile` and the year level `YYYY/Makefile`.

Performed `make quick_www` to accomplish the above and to test under macOS.

template/Makefile.year

@@ -228,30 +228,6 @@ clobber:
 	done
 	@echo '=-=-= ${YEAR} complete make $@ =-=-='
 
-install:
-	@echo '=-=-= ${YEAR} begin make $@ =-=-='
-	@echo
-	@for i in ${ENTRIES}; do \
-	    echo "=-= start ${YEAR}/$$i =-="; \
-	    echo "(cd $$i && ${MAKE} $@)"; \
-	    (cd $$i && ${MAKE} $@); \
-	    echo "=-= end ${YEAR}/$$i =-="; \
-	    echo; \
-	done
-	@echo '=-=-= ${YEAR} complete make $@ =-=-='
-
-indent.c:
-	@echo '=-=-= ${YEAR} begin make $@ =-=-='
-	@echo
-	@for i in ${ENTRIES}; do \
-	    echo "=-= start ${YEAR}/$$i =-="; \
-	    echo "(cd $$i && ${MAKE} $@)"; \
-	    (cd $$i && ${MAKE} $@); \
-	    echo "=-= end ${YEAR}/$$i =-="; \
-	    echo; \
-	done
-	@echo '=-=-= ${YEAR} complete make $@ =-=-='
-
 genpath:
 	@echo '=-=-= IOCCC begin make $@ =-=-='
 	@${RM} -f .tmp.genpath
@@ -292,6 +268,63 @@ new_entry:
 	  ${FMT} | ${SED} -e '2,$$s/^/\t/' -e 's/$$/ \\/' -e '$$s/ \\//'
 
 
+########################
+# extended utility rules
+########################
+
+.PHONY: indent_clean indent_clobber
+
+# you may be able to misunderstand the source by reading indent.c
+#
+indent.c:
+	@echo '=-=-= ${YEAR} begin make $@ =-=-='
+	@echo
+	@for i in ${ENTRIES}; do \
+	    echo "=-= start ${YEAR}/$$i =-="; \
+	    echo "(cd $$i && ${MAKE} $@)"; \
+	    (cd $$i && ${MAKE} $@); \
+	    echo "=-= end ${YEAR}/$$i =-="; \
+	    echo; \
+	done
+	@echo '=-=-= ${YEAR} complete make $@ =-=-='
+
+indent_clean: clean
+	@echo '=-=-= ${YEAR} begin make $@ =-=-='
+	@echo
+	@for i in ${ENTRIES}; do \
+	    echo "=-= start ${YEAR}/$$i =-="; \
+	    echo "(cd $$i && ${MAKE} $@)"; \
+	    (cd $$i && ${MAKE} $@); \
+	    echo "=-= end ${YEAR}/$$i =-="; \
+	    echo; \
+	done
+	@echo '=-=-= ${YEAR} complete make $@ =-=-='
+
+indent_clobber: indent_clean clobber
+	@echo '=-=-= ${YEAR} begin make $@ =-=-='
+	@echo
+	@for i in ${ENTRIES}; do \
+	    echo "=-= start ${YEAR}/$$i =-="; \
+	    echo "(cd $$i && ${MAKE} $@)"; \
+	    (cd $$i && ${MAKE} $@); \
+	    echo "=-= end ${YEAR}/$$i =-="; \
+	    echo; \
+	done
+	@echo '=-=-= ${YEAR} complete make $@ =-=-='
+
+install:
+	@echo '=-=-= ${YEAR} begin make $@ =-=-='
+	@echo
+	@for i in ${ENTRIES}; do \
+	    echo "=-= start ${YEAR}/$$i =-="; \
+	    echo "(cd $$i && ${MAKE} $@)"; \
+	    (cd $$i && ${MAKE} $@); \
+	    echo "=-= end ${YEAR}/$$i =-="; \
+	    echo; \
+	done
+	@echo '=-=-= ${YEAR} complete make $@ =-=-='
+
+
 ##################
 # 1337 hacker rulz
 ##################