fixed logos
- fixed logo and icons
- added option -spendzeroconfchange to workaround tx malleability problem
    as in https://github.com/bitcoin/bitcoin/pull/3651
- added seed nodes
- added checkpoints
- Chinese translations fixed
- difficulty field in getinfo, getmininginfo, getdifficulty now return
    the same as getwork: the size of the primes measured in bits. Note
    that this is not linear: 1500 is not 3x harder than 1000. It's like
    700 times harder.
- fixed DoS (crash) vulnerability in PoW calculation
Merge branch '0.8.6-ric' of https://github.com/riecoin/riecoin into 0.8.6-ric