Update Ubunto 18.04 avconv to ffmpeg

ws/Docbook/Preprocess/make.image

@@ -17,8 +17,8 @@ include mediaobjects.list
 	cd $(@D);pdf2svg $(*F).pdf $(*F).pdf.svg
 
 %.webm.mp4:%.webm
-	avconv -y -i $< -vcodec libx264 -acodec aac -strict -2 -r 10 $<.mp4
-	avconv -i $< -vframes 1 $<.png
+	ffmpeg -y -i $< -vcodec libx264 -acodec aac -strict -2 -r 10 $<.mp4
+	ffmpeg -i $< -vframes 1 $<.png
 
 
 #avconv -y -i q.webm -vcodec libx264 -acodec aac -strict -2 -r 10 target/src/_Resources/Video/Ref/Video/jdbcDriverConfig.webm.mp4 

ws/Docbook/Preprocess/make.rules

@@ -145,7 +145,7 @@ SAXONCMD=java -cp "${DBOOK_XSL}/tools/lib/saxon9he.jar:/usr/share/java/xercesImp
 # PDF
 # See http://stackoverflow.com/questions/39786947/how-to-convert-to-pdf-from-xsl-fo-with-mathml/39796975
 %.pdf: %.print.xml
-	/usr/share/hdm-fop/fop-2.2/fop/fop -xml $*.print.xml -xsl ${DBOOK_XSL_CUSTOM}/pdf/docbookHdm.xsl -pdf ${*}.pdf
+	/usr/share/hdm-fop/fop-2.3/fop/fop -xml $*.print.xml -xsl ${DBOOK_XSL_CUSTOM}/pdf/docbookHdm.xsl -pdf ${*}.pdf
 
 %.fo: %.print.xml # for debugging
 	${SAXON6CMD} $*.print.xml ${DBOOK_XSL_CUSTOM}/pdf/docbookHdm.xsl ${dbookXslPdfParam} > $*.fo