In the dialogs, every node has a "Text"-option.
It would be very convenient to have the possibility to embed lua variables from
the dialog into the option string.

This could be used for example with a variable traing post cost for lessons.
E.g.:
Kevin wants 300 circs and 2 * (told_lessons + 1) training points for the next
lessons.

Tux' answer should be something like
Text=_string.format("Yes, please teach me. (costs 300 circuits, %d training
points)", 2 * (told_lessons + 1))

Yep, this would be very useful.

We should also have a possebility to display one of some random Text_= strings.

An implementation can be found here:
http://rb.freedroid.org/r/1665/