Trace

Still requires a few fixes, but the main part is done.
As I understand kernel developers tend not to write deep recursive functions because of the limited and small stack size.
However, if an overflow is possible, it can happen in kt_trace_switch as well, and in that case we won't be able to restore any stacks in that part.
I think it's better to increase KT_MAX_STACK_FRAMES if we hit the limit sometime.