Support file names containing single quotes

This commit improves the support for file names containing special
characters inside “Typeset & View (PDF)”. We should now be able to
translate files with names such as `hel'lo.tex`.
Handle file names containing double quotes

We display an error message if the file name contains double quotes when
we invoke “Typeset & View (PDF)”. While it may well be that someone
wants to use such a file name, it seems that the various tex engines
have problems with file names containing double quotes.