Refactor AccountID (RIPD-953):

All AccountID functionality is removed from RippleAddress and
replaced with free functions. The AccountID to string conversion
cache is factored out as an explicit type with an instance in
the Application object. New base58 conversion functions are used,
with no dependence on OpenSSL.

All types and free functions related to AccountID are consolidated
into one header file. Routines to operate on "tokens" are also
introduced and consolidated into a single header file.

A token one of the cryptographic primitives used in Ripple:

    Secret Seed
    Server Public Key
    Server Secret Key
    Account ID
    Account Public Key
    Account Private Key

    and these deprecated primitives:

    Account Family Seed
    Account Family Generator

src/ripple/app/ledger/Ledger.cpp

@@ -43,6 +43,7 @@
 #include <ripple/json/to_string.h>
 #include <ripple/nodestore/Database.h>
 #include <ripple/protocol/HashPrefix.h>
+#include <ripple/protocol/types.h>
 #include <beast/module/core/text/LexicalCast.h>
 #include <beast/unit_test/suite.h>
 #include <boost/optional.hpp>
@@ -65,7 +66,7 @@ makeGenesisAccount (AccountID const& id,
     std::shared_ptr<SLE> sle =
         std::make_shared<SLE>(ltACCOUNT_ROOT,
             getAccountRootIndex(id));
-    sle->setFieldAccount (sfAccount, id);
+    sle->setAccountID (sfAccount, id);
     sle->setFieldAmount (sfBalance, drops);
     sle->setFieldU32 (sfSequence, 1);
     return sle;
@@ -76,8 +77,10 @@ makeGenesisAccount (AccountID const& id,
 //        other constructor with appropriate parameters, and
 //        then create the master account / flush dirty.
 //
-Ledger::Ledger (RippleAddress const& masterID, std::uint64_t startAmount)
-    : mTotCoins (startAmount)
+// VFALCO Use `AnyPublicKey masterPublicKey`
+Ledger::Ledger (RippleAddress const& masterPublicKey,
+        std::uint64_t balanceInDrops)
+    : mTotCoins (balanceInDrops)
     , seq_ (1) // First Ledger
     , mCloseTime (0)
     , mParentCloseTime (0)
@@ -90,7 +93,8 @@ Ledger::Ledger (RippleAddress const& masterID, std::uint64_t startAmount)
         getApp().family(), deprecatedLogs().journal("SHAMap")))
 {
     auto sle = makeGenesisAccount(
-        masterID.getAccountID(), startAmount);
+        calcAccountID(masterPublicKey),
+            balanceInDrops);
     WriteLog (lsTRACE, Ledger)
             << "root account: " << sle->getJson(0);
     unchecked_insert(std::move(sle));
@@ -603,7 +607,7 @@ bool Ledger::saveValidatedLedger (bool current)
                 sql.reserve (sql.length () + (accts.size () * 128));
 
                 bool first = true;
-                for (auto const& it : accts)
+                for (auto const& account : accts)
                 {
                     if (!first)
                         sql += ", ('";
@@ -615,7 +619,7 @@ bool Ledger::saveValidatedLedger (bool current)
 
                     sql += txnId;
                     sql += "','";
-                    sql += it.humanAccountID ();
+                    sql += getApp().accountIDCache().toBase58(account);
                     sql += "',";
                     sql += ledgerSeq;
                     sql += ",";
@@ -703,7 +707,6 @@ loadLedgerHelper(std::string const& sqlSuffix)
 
     if (!db->got_data ())
     {
-        std::stringstream s;
         WriteLog (lsINFO, Ledger) << "Ledger not found: " << sqlSuffix;
         return std::make_tuple (Ledger::pointer (), ledgerSeq, ledgerHash);
     }
@@ -1236,7 +1239,7 @@ bool Ledger::pendSaveValidated (bool isSynchronous, bool isCurrent)
 void
 ownerDirDescriber (SLE::ref sle, bool, AccountID const& owner)
 {
-    sle->setFieldAccount (sfOwner, owner);
+    sle->setAccountID (sfOwner, owner);
 }
 
 void
@@ -1362,31 +1365,6 @@ cachedRead (Ledger const& ledger, uint256 const& key,
     return sle;
 }
 
-AccountState::pointer
-getAccountState (Ledger const& ledger,
-    RippleAddress const& accountID,
-        SLECache& cache)
-{
-    auto const sle = cachedRead (ledger,
-        getAccountRootIndex(accountID.getAccountID()),
-            cache);
-    if (!sle)
-    {
-        // VFALCO Do we really need to log here?
-        WriteLog (lsDEBUG, Ledger) << "Ledger:getAccountState:" <<
-            " not found: " << accountID.humanAccountID () <<
-            ": " << to_string (getAccountRootIndex (accountID));
-
-        return {};
-    }
-
-    // VFALCO Does this ever really happen?
-    if (sle->getType () != ltACCOUNT_ROOT)
-        return {};
-
-    return std::make_shared<AccountState>(sle, accountID);
-}
-
 boost::optional<uint256>
 hashOfSeq (Ledger& ledger, LedgerIndex seq,
     SLECache& cache, beast::Journal journal)
@@ -1459,6 +1437,35 @@ hashOfSeq (Ledger& ledger, LedgerIndex seq,
     return boost::none;
 }
 
+void
+injectSLE (Json::Value& jv,
+    SLE const& sle)
+{
+    jv = sle.getJson(0);
+    if (sle.getType() == ltACCOUNT_ROOT)
+    {
+        if (sle.isFieldPresent(sfEmailHash))
+        {
+            auto const& hash =
+                sle.getFieldH128(sfEmailHash);
+            Blob const b (hash.begin(), hash.end());
+            std::string md5 = strHex(b);
+            boost::to_lower(md5);
+            // VFALCO TODO Give a name and move this constant
+            //             to a more visible location. Also
+            //             shouldn't this be https?
+            jv[jss::urlgravatar] = str(boost::format(
+                "http://www.gravatar.com/avatar/%s") % md5);
+        }
+    }
+    else
+    {
+        jv[jss::Invalid] = true;
+    }
+}
+
+//------------------------------------------------------------------------------
+
 bool
 getMetaHex (Ledger const& ledger,
     uint256 const& transID, std::string& hex)