difficulty test example [EXAMPLE]

[winsvega]

retesteth develop branch: ethereum/retesteth#152

Here some comments:

# Test generate for all provided networks
        "network" : [ "London"],
# For blocknumbers from  B1 to B2 with step dB   // or array of values
        "blocknumber" : "[100000-100010;5]",
# For timestamp intervals from  T1 to T2 with step dT // or array of values
        "timestampDiff" : "[1-2;1]",
# For parentDifficulty intervals from  PD1 to PD2 with step dPD // or array of values
        "parentDifficutly" : ["131415"],
# For current block having number of uncles (array of values, max 2 values)
        "hasUncles" : [1]

the test calculate difficulty formula given above input parameters using geth evm t8n