factored git-revision out into rule. Added release rule.

Makefile

@@ -2,6 +2,7 @@ PHPDOC ?= support/pear/phpdoc
 JSDOC ?= jsdoc
 PKG_VERSION = $(shell awk '/version/ { print $$3 }' extension/ext_emconf.php  | sed "s/'//g")
 NIGHTLY_DATE = $(shell date '+%Y%m%d')
+RELEASE_DATE = $(shell date '+%Y%m%d%H%M')
 GIT_REVISION_SHORT = $(shell git rev-parse --short HEAD || true)
 GIT_REVISION_LONG = $(shell git rev-parse HEAD || true)
 EXTENSION_CONTENT = Classes Configuration Documentation qfq Resources ext_emconf.php ext_localconf.php ext_tables.php ext_icon.png config.example.ini
@@ -22,13 +23,18 @@ qfq.zip:
 clean:
 	rm -f qfq_$(PKG_VERSION).zip
 
-nightly: bootstrap
+git-revision:
 	echo $(GIT_REVISION_LONG) > extension/revision.git
+
+nightly: bootstrap git-revision
 	cd extension; zip -r ../qfq-$(NIGHTLY_DATE)  $(EXTENSION_CONTENT) revision.git -x config.ini
 
-snapshot: bootstrap
-	echo $(GIT_REVISION_LONG) > extension/revision.git
-	cd extension ; zip -r ../qfq-$(NIGHTLY_DATE)-$(GIT_REVISION_SHORT)  $(EXTENSION_CONTENT) revision.git -x config.ini
+snapshot: bootstrap git-revision
+	cd extension ; zip -r ../qfq-$(NIGHTLY_DATE)-$(GIT_REVISION_SHORT) $(EXTENSION_CONTENT) revision.git -x config.ini
+
+release: bootstrap git-revision
+	test -z "$${VERSION}" && echo "Set VERSION environment variable to the release version (fmt: maj.min.micro)"
+	cd extension ; zip -r "../qfq.$${VERSION}_$${RELEASE_DATE}" $(EXTENSION_CONTENT) revision.git -x config.ini
 
 
 t3sphinx:
@@ -84,4 +90,4 @@ phpdoc: .phpdocinstall
 	mkdir -p doc/plantuml/php
 	touch $@
 
-.PHONY: nightly maintainer-clean
+.PHONY: nightly maintainer-clean snapshot release revision.git