add makefile back for building the sources

Makefile

+FILES := \
+  HsH-article.cls \
+  HsH-report.cls \
+  HsH-standalone.cls \
+  config.tex
+
+.PHONY: src
+src: $(FILES)
+$(FILES) &: HsH-Classes.ins HsH-Classes.dtx
+	latex HsH-Classes.ins
+
+.PHONY: clean
+clean:
+	rm -f $(FILES)