Bump version to 2.0.

Note that configure hadn't been checked in a few times so it has more
changes, catching up with the last few changes to congifure.in as
well.

configure.in

@@ -6,7 +6,7 @@ AC_CONFIG_HEADER(config.h)
 
 # Set VERSION so we only need to edit in one place (i.e., here)
 AC_SUBST(VERSION)
-VERSION=1.6
+VERSION=2.0
 
 # NEXTSTEP stuff
 if test -f /usr/lib/NextStep/software_version -o -f /System/Library/CoreServices/software_version ; then