Added targets dvi, pdf, and ps, to make all of the documents in those formats.
diff --git a/Doc/Makefile b/Doc/Makefile
index cb6008e..1ab0c13 100644
--- a/Doc/Makefile
+++ b/Doc/Makefile
@@ -90,17 +90,17 @@
 # Main target
 all:	all-ps
 
-all-dvi:
+all-dvi dvi:
 	(cd paper-$(PAPER); \
 		$(MAKE) srcdir=.. VPATH=.. TEXINPUTS=$(TEXINPUTS) \
 		-f ../Makefile do-dvi)
 
-all-pdf:
+all-pdf pdf:
 	(cd paper-$(PAPER); \
 		$(MAKE) srcdir=.. VPATH=.. TEXINPUTS=$(TEXINPUTS) \
 		-f ../Makefile do-pdf)
 
-all-ps:
+all-ps ps:
 	(cd paper-$(PAPER); \
 		$(MAKE) srcdir=.. VPATH=.. TEXINPUTS=$(TEXINPUTS) \
 		-f ../Makefile do-ps)