Grab `make release` from Pidgin

This brings in `make version-check` which is nice.  It's been modified:
irrelevant bits were removed and changes were made to support git.

Makefile.am

@@ -8,6 +8,27 @@ README: doc/index.html
 SUBDIRS = src doc examples mibs
 EXTRA_DIST = build_setup.nsi.in README
 MAINTAINERCLEANFILES = README
+
+version-check:
+# We don't want to release development versions.
+	test x`echo $(PACKAGE_VERSION) | grep dev` = x
+
+# For all releases, check the ChangeLogs.
+	head ChangeLog | grep "^version $(PACKAGE_VERSION) (`date +%m/%d/%Y`):$$" >/dev/null
+
+# Ensure we're working from a tag...
+	HEAD=`git rev-parse --verify HEAD` && test `git tag -l --contains $$HEAD | wc -l` -gt 0
+# ... and have no changes in the working copy.
+	git status | grep -q "working directory clean"
+
+release: version-check distcheck packages
+
+packages:
+	gpg -ab $(PACKAGE)-$(PACKAGE_VERSION).tar.gz
+	gpg -ab $(PACKAGE)-$(PACKAGE_VERSION).tar.bz2
+	gpg --verify $(PACKAGE)-$(PACKAGE_VERSION).tar.gz.asc $(PACKAGE)-$(PACKAGE_VERSION).tar.gz
+	gpg --verify $(PACKAGE)-$(PACKAGE_VERSION).tar.bz2.asc $(PACKAGE)-$(PACKAGE_VERSION).tar.bz2
+
 if CYGWIN_BUILD
 if CYGWIN_BUILD_SETUP_EXE
 bin_SCRIPTS=docsis_setup.exe