Remove latex.out/ on --clean-all if empty
Remove latex.out/ on --clean-all if empty

Closes #10

mhoogendoorn/latexrun,FranzSkuffka/latexrun,apuignav/latexrun,temporaer/latexrun,temporaer/latexrun,msullivan/latexrun,mhoogendoorn/latexrun,aclements/latexrun,aclements/latexrun,FranzSkuffka/latexrun,msullivan/latexrun,apuignav/latexrun