Add line wrapping and cursor key repeats to manual memoryedit

[darrenfreeman]

I am using "DiagROM V1.3 BETA - 21-Feb-22".

I have been doing some diagnostics on the address busses. Often, I just open the "manual memoryedit" function, and move around to watch the address lines toggling. It would be useful if the cursor keys would have a keyrepeat, so that I can just hold one of them down while watching the scope. In addition, I would like the end of one line to wrap to the start of the next, and vice versa, so it's possible to count through every possible address, without watching the screen. (Currently, the cursor won't move beyond the left or right end of the line.)

I don't think this change would impact on other use-cases, and it would be occasionally useful. Could you please consider it, and thanks for this wonderful tool!