v3.0
build: allow compilation on cygwin
revert 2002 change that removed "Binary " from "files A and B differ"
maint: update all FSF copyright year lists to include 2010
diff -F/-p: don't depend on locale-specific white-space definition
portability: avoid "diff - ..." failure at least on *BSD and Solaris
Followon improvements for the fix for Debian bug 577832.
avoid compilation failure on systems lacking both fork and vfork
maint: remove now-useless #if HAVE_HEADER_H guards