[WIP] Fix page__alto and alto__page

[zuphilip]

This is work in progress and I may need some help. Currently the transformations alto2page and page2alto are present but not everything is producing some reasonable output:

• In the web GUI any of these transformations leads to an empty file. I haven't found out why...
• The alto2page transformation seems to work in the CLI but the debugging messages (bash -x resp. set -x) were unusual. I tried to toggle them on only when the debug option is toggled twice. However, this then only works for the main script and will not for any otherwise called script. Can this been improved?
• The page2alto transformation in the CLI produces some output but that is again a page file. For this we need another parameter which I tried to pass now. This should be further tested and reviewed whether the approach looks reasonable for you bash script experts.

Do not yet merge this, as we need first to finish this PR together. CC @kba @stweil

[stweil]

In the web GUI any of these transformations leads to an empty file.

The web interface uses STDIN and STDOUT to pass data to and from ocr-transform. So it runs ocr-transform page alto - - for example. This does not work because the current scripts handle output to STDOUT, but don't support input from STDIN. They expect a real file.

[zuphilip]

Okay, I get some results by adding

if [[ "$3" = "-" ]];then
    #echo "$0 $1 $2 $3"
    INFILE="$(mktemp)"
    cp /dev/stdin "$INFILE"
fi

but I don't understand why the order of variables change ($3 vs $1). Moreover, I am not sure that this is the way to go. Any advice?

[stweil]

Based on your work I created a new PR #106 which should work now. I already installed it, so you can try the web interface.

[zuphilip]

Superseeded by #106.