adding test filling the entire tracing buffer
only set arena pointers when buckets could be allocated
allocate traces up to max capacity

we use the main bucket only as starting point, then iterate over all of
them
Merge pull request #8 from uucidl/feature/stop-when-full

stop when the buffers are full. SPDR uses the full capacity of the buffer and this corrects the event sequence that would sometimes be garbled towards the end before (due to buckets being used in a non uniform way)