Add makekeypair to generate ECDSA keys

Use this to generate keys for use in alert.cpp to replace old Litecoin keys. All forks of Darkcoin are affected by this issue (I can tell that much by your subsidy function declaring the diff (nBits) but not using it), and as you are also (we are Hirocoin) a security focussed coin, you need to update this or your clients will receive messages every time Litecoin sends out a network broadcast.

Reference: https://github.com/HiroSatou/darkcoin/commit/ff3bb3d69ef573b9a01f2aecfe9319564eec25eb

Please take this security notice seriously, all Darkcoin forks are affected. If you know of any others please contact them regarding the fix too :-) Let's fix some of this segregation in the crypto community - we're all working towards the same thing, right?