message: Simplify and remove dead code from uahf_fork.cpp
  while at it also change comments to reflect the fact
  we move from time based to height based activation for
  the Aug, 1st 2017 protocol upgrade.
diff: bool IsTxProbablyNewSigHash(const CTransaction &tx)
  {
  - // bool newsighash = false;
  bool oldsighash = false;
  for (auto txin : tx.vin)
  {
  @@ -26,14 +25,8 @@ bool IsTxProbablyNewSigHash(const CTransaction &tx)
  {
  if (!data.empty())
  {
  - if (data.back() & SIGHASH_FORKID)
  - {
  - // newsighash = true;
  - }
  - else
  - {
  - oldsighash = true;
  - }
  + if
  + !(data.back() & SIGHASH_FORKID) { oldsighash = true; }
  }
  }
  }
  @@ -44,24 +37,12 @@ bool IsTxUAHFOnly(const CTxMemPoolEntry &txentry)
  {
  if ((txentry.sighashType & SIGHASH_FORKID) || (txentry.sighashType == 0))
  {
  - // LOGA("txn is UAHF-specific\n");
  return true;
  }
  return false;
  }
  -// According to UAHF spec there are 2 pre-conditions to get the fork activated:
  -//
  -// 1) First step is waiting for the first block to have GetMedianTimePast() (GMTP)
  -// be higher or equal then 1501590000 (Aug 1st 2017, 12:20:00 UTC). This block would
  -// be the last in common with the other branch to the fork.
  -// Let's call this block x-1. The match of this conditions will be called "Fork Enabled"
  -//
  -// 2) x-1 could be extended only by a block bigger than 1MB, so that size(block x) > 1MB
  -// The match of this conditions will be called "Fork Activated"
  -
  -// return true for every block from fork block and forward [x,+inf)
  -// fork activated
  +// return true for every block from fork block and forward [consensusParams.uahfHeight,+inf)
  bool UAHFforkActivated(int height)
  {
  const Consensus::Params &consensusParams = Params().GetConsensus();
  @@ -73,7 +54,7 @@ bool UAHFforkActivated(int height)
  }
  // This will check if the Fork will be enabled at the next block
  -// i.e. we are at block x - 1, [x-1, +inf]
  +// i.e. we are at block x - 1, [consensusParams.uahfHeight-1, +inf]
  // state fork: enabled or activated
  bool IsUAHFforkActiveOnNextBlock(int height)
  {
  @@ -83,8 +64,8 @@ bool IsUAHFforkActiveOnNextBlock(int height)
  return false;
  }
  -// return true only if 1st condition is true (Median past time > UAHF time)
  -// and not the 2nd, i.e. we are at precisely [x-1,x-1]
  +// return true only if 1st condition is true (Median past time > fork time)
  +// and not the 2nd, i.e. we are at precisely [consensusParams.uahfHeight-1,consensusParams.uahfHeight-1]
  // state: fork enabled
  bool UAHFforkAtNextBlock(int height)
  {
  