RISCV sp and epc corruption
Sporadic exceptions appear in most applications, but at an increased rate when running multicore with kernel (i.e. philosophers_dinner). Kernel and user stack pointers get swapped and corrupted, or epc is zeroed.
Timer interrupt influence was already discarded. The main hypotheses are in Context's push/pop or interrupt handling, with a possibility of not dealing with privilege chances correctly.
Initial debug code was committed to the branch 'bewiahn'.