A fix to inclusion of posttitle.tex

[mattpitkin]

I've got a fix to checking whether the 'posttitle.tex' file exists - previously if localdir and buildir were different, and --relative-links was set then the check for whether this file exists would fail even if it did exist in localdir.

Also, I've swapped where posttitle.tex is included to be before the abstract.

[mattpitkin]

I've just seen that the second point I make would be fixed by the suggestion from #5 in commit 29757fb

[mattpitkin]

I've just added another patch (29757fb) that fixes how figures and captions are included in the case that locadir and builddir are different and --relative-links are used. Before this these were not included, or not included properly.

[eteq]

Alright, I finally got to this - there was a subtle bug due to figdir getting overridden and one other place that needed the "absolute" path instead of the relative one. But I managed to fix those and merge this into master. So thanks, @mattpitkin !