LaTeX template: fix footnotes in tables.

This requires the footnote package, which is imported only
if present.

See #208.  Thanks to Václav Haisman.

default.latex

@@ -123,6 +123,8 @@ $if(verbatim-in-note)$
 $endif$
 $if(tables)$
 \usepackage{longtable,booktabs}
+% Fix footnotes in tables (requires footnote package)
+\IfFileExists{footnote.sty}{\usepackage{footnote}\makesavenoteenv{long table}}{}
 $endif$
 $if(graphics)$
 \usepackage{graphicx,grffile}