no bug/feature but question: how to save and restore random generator state (Support #274)

Hello,

I am still thinking of a specific question type, in which I have n question, n answers, in which the answers and question are both to be randomized and then grouped together.
Then I want to put the questions and answer-option in one matrix appearing random per student.

For that I need to be able to randomize 2 pairs of registers. The element-registers are of same length.
My question is, how can I fetch the state of the random generator before shuffling one register, shuffle the register and then set the random generator to the previous state and shuffle the next register.
This would allow me to randomize the answers in the answer column and put the rows of choices in the same (random) order.
After that I could take the rows of choices as special questions, and randomize them, together with the rows as second register pair.
The rows would then be put together to form the matrix, the questions and answers in the now set random order in a table above the matrix, on each row a (sequential) number, a question, a sequential letter and the (typically unrelated, because of randomisation) answer.

This would allow be to put something between 15 to 20 q-a pairs on one A4 sheet, which would be the equivalent of 15-20 MC questions with 15-20 choices each. In the traditional way that would take up 6 sheets.

This is a follow up on #190 for the question type I want to implement.