several cleanup steps

- fully incorporated back sayamindu's stuff for dealing with encrypted
  signatures files (not a bad idea!)

- removed an old uw-header file from a previous version

Makefile

@@ -1,23 +1,24 @@
 #!/usr/bin/make
-.RECIPEPREFIX +=
-SIGIMAGE = figures/signature.png.gpg
 
-all: $(patsubst %.tex,%.pdf,$(wildcard *.tex)) 
+ENC_SIGIMAGE = figures/signature.pdf.gpg
+DEC_SIGIMAGE = figures/signature.pdf
 
-%.pdf: update-sig %.tex 
+all: figures/signature.pdf $(patsubst %.tex,%.pdf,$(wildcard *.tex))
+
+figures/signature.pdf:
+	gpg --yes --output $(DEC_SIGIMAGE) --decrypt $(ENC_SIGIMAGE)
+
+%.pdf: %.tex
 	latexmk -f -xelatex $<
 
-<update-sig:
-    gpg --yes --output figures/signature.png --decrypt $(SIGIMAGE)
-
-clean: 
+clean:
 	latexmk -C *.tex
 	$(RM) -f *.tmp *.run.xml
-	$(RM) -f figures/signature.png
+	$(RM) -f $(DEC_SIGIMAGE)
 
 viewpdf: all
 	evince *.pdf
 
 pdf: all
 
-.PHONY: clean all
+.PHONY: clean all update-sig