Improves the readability of the output from jats2epub.
Also jats2epub no longer expects to find xmlcalabash, kindlegen and epubcheck
in the programs subfolder of the jats2epub root folder.

Instead those commands are expected to be avaliable from the path in any folder.

If installing those programs in the path is difficult, instead use jats2epub-legacy
and make sure xmlcalabash, kindlegen and epubcheck are installed in the programs
subfolder of the jats2epub root folder.