add watch target

Automatically rebuild whenever a .tex file is changed.

Makefile

@@ -24,6 +24,9 @@ $(PDFNAME).pdf: $(TEXMAINFILE) *.tex
 view: $(PDFNAME).pdf
 	$(PDFVIEWER) $(PDFNAME).pdf &
 
+watch:
+	while true; do make --silent; sleep 2; done
+
 clean:
 	$(MKLATEX) -CA
 	rm -f $(PDFNAME).pdf *.{aux,bbl,bcf,blg,cb,fdb_latexmk,fls,lof,log,lot,out,run.xml,rel,synctex.gz,toc}