there, i fixed it

turns out that checkQuizfinished didn't get called due to work on
loading-by-code. thus the deprecated flags were not set correctly and
scene stepping did not happen. i also added functionality to
automatically calculate the dialog font size based on dialogbox
dimensions. this will be a relative value configurable by changing
gPercentageFontSize in helper.js.

i advice every future developer working with the dialog system do
completely discard it and build a proper one. XD