Problems while app migration from 5.0 to 6.0 toolchain

[Holdwyn]

I was faced with some problems while moving our app from the Python generator to the qx compiler. Basically I followed the migration notes under https://qooxdoo.org/documentation/6.0/#/development/compiler/migration

1. The script tag is wrong, src has to be "${appPath}index.js". The compiler has issued a suitable warning.
2. It was very hard, in fact I just fixed it with the great support of @johnspackman, to find out how to include local libraries. Searching the docs I was using the suggestion under https://qooxdoo.org/documentation/6.0/#/development/cli/packages?id=install-a-library to use "install --from-path" but that's probably not the right solution.
3. Using the libraries setting in compile.json without adding the own directory ("."), leads to an unspecific error: