The backend address in the environment file needs to either be localhost 
for using the app from the (host system's) browser of the internal 
docker name (backend-mock) so the frontend container can reach it. SO 
the testcenterUrl can either be reached from the host or fromt he 
frontend container but not both. This makes it so, that the e2e tests 
use a specific environment (defined in angular.json) which uses a 
different environment file for running e2e test within the frontend 
container.

instad the internal one

Now we again have a dev and prod variant and the user needs to run 'make 
init-dev-config'at first time setup.

rename TERMINATING to TERMINATED wo have the one reported to backend/monitor to be TERMINATED and teh internale state (former TERMINATED) wich cames when locking was successful to FINISHED (not LOCKED because possible future confusion)

new booklet config parameters implemented: page_navibuttons, unit_menu, unit_screenheader, unit_title (not all options)

introducing srcdoc polyfill for edge

interceptor + php slim ...
compiles without errors, login working