Give images integer sizes

pdftoppm always rounds up to the next highest integer when working out
the size of the bitmaps.  If we do this too, we avoid blurriness.  This
is most noticable in page sizes, like a4, that are not integer sized in
pts.
Set latex option -interaction=nonstopmode

On newer versions, -halt-on-error doesn't.
Use files/resolve to normalize path in backwards sync

The normalization may resolve issue #11.