examples: d: duplicate the example as "simple" and "calc"

* examples/d/Makefile, examples/d/calc.d, examples/d/calc.test,
examples/d/calc/local.mk: Move into...
* examples/d/calc, examples/d/simple: these new directories.

examples/d/simple/Makefile

@@ -0,0 +1,25 @@
+# This Makefile is designed to be simple and readable.  It does not
+# aim at portability.  It requires GNU Make.
+
+BISON = bison
+DC = dmd
+XSLTPROC = xsltproc
+
+all: calc
+
+%.d %.xml %.gv: %.y
+	$(BISON) $(BISONFLAGS) --xml --graph=$*.gv -o $*.d $<
+
+%: %.d
+	$(DC) $(DCFLAGS) $<
+
+run: calc
+	@echo "Type arithmetic expressions.  Quit with ctrl-d."
+	./$<
+
+html: calc.html
+%.html: %.xml
+	$(XSLTPROC) $(XSLTPROCFLAGS) -o $@ $$($(BISON) --print-datadir)/xslt/xml2xhtml.xsl $<
+
+clean:
+	rm -f calc calc.d calc.xml calc.gv calc.html *.o