prepare for compressed releases

vars

+VERSION != git tag | tail -1
+QR_TARGET != grep mailto: README.md | cut -d: -f2,3
+
+COMPRESS = gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.5 -dNOPAUSE -dQUIET -dBATCH -dPrinted=false -sOutputFile=$@ $<
+
 CP := ln -f
 BOOK := $(shell basename "$$(pwd)")
 DROSS := $(shell head -1 .gitignore)
 COMPILER := latexmk -auxdir=$(DROSS) -pdflua -silent -shell-escape -r config/.latexmkrc -jobname=$(BOOK)
+RELEASE := $(BOOK)-$(VERSION).pdf
 GLOS := makeglossaries -d $(DROSS)
 RUN := lualatex -output-directory $(DROSS) -shell-escape
 CLEAN := $(RM) -r $(DROSS) qr.tex *.pdf svg-inkscape
 DEPS := *tex config/*sty
-QR_TARGET != grep mailto: README.md | cut -d: -f2,3