evolve: fixing obscache invalidation This was missing a call to the parent's destroyed(), such that any transaction after stripping some nodes would result in a crash (by attempting to read nodes which were stripped).

obshashrange: warm the cache at the end of each transaction This will help having warmed cache for read only client. The warming is still imperfect in case of markers that trigger a reset, but we are in a better place than what we used to be.

obshashrange: warm cache outside of loops The performance impact will be lower