[graphics] Rubber doesn't understand includegraphics with dots in filenames

[Sebastian Kapfer]

If a filename includes a dot, like

\includegraphics{{empty1.0}.png}

Rubber doesn't know what to do with that, even though pdfLaTeX can cope:
Rubber then says

doc.tex:5: graphics `{empty1.0}.png' not found

Test case for this was committed as Git c6f8e5ceb16f198966bbf2eac4e65b722e773df1.

[Sebastian Kapfer (caci)]

A workaround covering some of the more common cases is found in githash 596dcd6c097864f70f5231069733e6f747046301, improving upon earlier 92d6e37f62a54361be4b87e37cd64d8c4cfea5a1.

There certainly remain more ways to trick Rubber with working but questionable TeX code, but that's beside the point.