Remove mining/fee related code / rpc commands

[scravy]

bitcoin has quite a few mining/fee related commands which are not relevant for unit e (estimation of fees for example is gonna be completely replaced by exact fees for a given transaction).

Thus the following rpc commands and related code (miner.cpp, not pos/miner.cpp) are not needed and would potentially only add to a unite-cli user's confusion:

    { "mining",             "getnetworkhashps",       &getnetworkhashps,       {"nblocks","height"} },
    { "mining",             "getmininginfo",          &getmininginfo,          {} },
    { "mining",             "prioritisetransaction",  &prioritisetransaction,  {"txid","dummy","fee_delta"} },
    { "mining",             "getblocktemplate",       &getblocktemplate,       {"template_request"} },
    { "mining",             "submitblock",            &submitblock,            {"hexdata","dummy"} },


    { "generating",         "generatetoaddress",      &generatetoaddress,      {"nblocks","address","maxtries"} },

    { "util",               "estimatefee",            &estimatefee,            {"nblocks"} },
    { "util",               "estimatesmartfee",       &estimatesmartfee,       {"conf_target", "estimate_mode"} },

    { "hidden",             "estimaterawfee",         &estimaterawfee,         {"conf_target", "threshold"} },