Make memory test not stop after error is found

[mankeli]

It would perhaps be useful to keep the memory test running even after errors are found.

For example I only saw bit 2 to be broken after running the test several times, swapped out the chip and bit 2 is not broken anymore. But now bit 5 gives errors after a longer period of running. I would have been nice to catch both of those on one go.

[keirf]

Well... maybe, I'm not sure how common this would be, really. Also in larger memory systems you would not know which memory area caused which bit error. Unless I updated the reporting, somehow.

Perhaps I should make it an option.