Remove confusing MAX_BLOCK_BASE_SIZE.

Some people keep thinking that MAX_BLOCK_BASE_SIZE is a separate
 size limit from the weight limit when it fact it is superfluous,
 and used in early tests before the witness data has been
 validated or just to compute worst case sizes.  The size checks
 that use it would not behave any differently consensus wise
 if they were eliminated completely.

Its correct value is not independently settable but is a function
 of the weight limit and weight formula.

This patch just eliminates it and uses the scale factor as
 required to compute the worse case constants.

It also moves the weight factor out of primitives into consensus,
 which is a more logical place for it.

src/merkleblock.cpp

@@ -153,7 +153,7 @@ uint256 CPartialMerkleTree::ExtractMatches(std::vector<uint256> &vMatch, std::ve
     if (nTransactions == 0)
         return uint256();
     // check for excessively high numbers of transactions
-    if (nTransactions > MAX_BLOCK_BASE_SIZE / 60) // 60 is the lower bound for the size of a serialized CTransaction
+    if (nTransactions > MAX_BLOCK_WEIGHT / MIN_TRANSACTION_WEIGHT)
         return uint256();
     // there can never be more hashes provided than one for every txid
     if (vHash.size() > nTransactions)