This will finally fix all block finding issues with a 4 way detection.
The find upstream method will continue to try other ways to find a
proper share until they are all exhausted or a match was found.
* Use stratum solution, create scrypt hash from block header
* Use pushpoold solution, create solution string from block header
* Use first available upstream share in timerange of block time
* Use *any* first available valid share older than time of block
This will fix#405 - no more unknown blocks. Ever.
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