Enhance Makefile to use build folder

Makefile

@@ -4,14 +4,17 @@ NAME=Masterarbeit
 LAST_EXPORT=`cat LAST_EXPORT`
 
 render:
-	pdflatex ${NAME}.tex
-	bibtex ${NAME}
-	pdflatex ${NAME}.tex
-	pdflatex ${NAME}.tex
+	mkdir build
+	pdflatex -output-directory build ${NAME}.tex
+	bibtex build/${NAME}
+	pdflatex -output-directory build ${NAME}.tex
+	pdflatex -output-directory build ${NAME}.tex
 
 diff:
-	git-latexdiff $(LAST_EXPORT) -- --main ${NAME}.tex --no-flatten -o diff.pdf
+	cd build; git-latexdiff $(LAST_EXPORT) -- --main ${NAME}.tex --no-flatten -o diff.pdf; cd ..
 
 clean:
-	rm -f *.aux *.bbl *.blg *.dvi *.log *.lol *.lot *.lof *.toc *.out *.synctex.gz *.bak
-	rm -f *.pdf
+	rm -rfv build
+
+show:
+	okular build/${NAME}.pdf