Seperate out wallet options in help message

Seperate out the wallet options in HelpMessage, and
don't show them if compiled with --disable-wallet.

Also add documentation for `-disablewallet` option.

src/init.cpp

@@ -194,10 +194,8 @@ std::string HelpMessage(HelpMessageMode hmm)
     strUsage += "  -conf=<file>           " + _("Specify configuration file (default: bitcoin.conf)") + "\n";
     strUsage += "  -datadir=<dir>         " + _("Specify data directory") + "\n";
     strUsage += "  -testnet               " + _("Use the test network") + "\n";
-
     strUsage += "  -pid=<file>            " + _("Specify pid file (default: bitcoind.pid)") + "\n";
     strUsage += "  -gen                   " + _("Generate coins (default: 0)") + "\n";
-    strUsage += "  -wallet=<file>         " + _("Specify wallet file (within data directory)") + "\n";
     strUsage += "  -dbcache=<n>           " + _("Set database cache size in megabytes (default: 25)") + "\n";
     strUsage += "  -timeout=<n>           " + _("Specify connection timeout in milliseconds (default: 5000)") + "\n";
     strUsage += "  -proxy=<ip:port>       " + _("Connect through SOCKS proxy") + "\n";
@@ -227,7 +225,6 @@ std::string HelpMessage(HelpMessageMode hmm)
     strUsage += "  -upnp                  " + _("Use UPnP to map the listening port (default: 0)") + "\n";
 #endif
 #endif
-    strUsage += "  -paytxfee=<amt>        " + _("Fee per kB to add to transactions you send") + "\n";
     strUsage += "  -debug=<category>      " + _("Output debugging information (default: 0, supplying <category> is optional)") + "\n";
     strUsage +=                               _("If <category> is not supplied, output all debugging information.") + "\n";
     strUsage +=                               _("<category> can be:");
@@ -264,23 +261,27 @@ std::string HelpMessage(HelpMessageMode hmm)
     strUsage += "  -rpcuser=<user>        " + _("Username for JSON-RPC connections") + "\n";
     strUsage += "  -rpcpassword=<pw>      " + _("Password for JSON-RPC connections") + "\n";
     strUsage += "  -rpcport=<port>        " + _("Listen for JSON-RPC connections on <port> (default: 8332 or testnet: 18332)") + "\n";
-
     strUsage += "  -rpcallowip=<ip>       " + _("Allow JSON-RPC connections from specified IP address") + "\n";
     strUsage += "  -rpcthreads=<n>        " + _("Set the number of threads to service RPC calls (default: 4)") + "\n";
     strUsage += "  -blocknotify=<cmd>     " + _("Execute command when the best block changes (%s in cmd is replaced by block hash)") + "\n";
-    strUsage += "  -walletnotify=<cmd>    " + _("Execute command when a wallet transaction changes (%s in cmd is replaced by TxID)") + "\n";
     strUsage += "  -alertnotify=<cmd>     " + _("Execute command when a relevant alert is received or we see a really long fork (%s in cmd is replaced by message)") + "\n";
-    strUsage += "  -upgradewallet         " + _("Upgrade wallet to latest format") + "\n";
     strUsage += "  -keypool=<n>           " + _("Set key pool size to <n> (default: 100)") + "\n";
-    strUsage += "  -rescan                " + _("Rescan the block chain for missing wallet transactions") + "\n";
-    strUsage += "  -salvagewallet         " + _("Attempt to recover private keys from a corrupt wallet.dat") + "\n";
     strUsage += "  -checkblocks=<n>       " + _("How many blocks to check at startup (default: 288, 0 = all)") + "\n";
     strUsage += "  -checklevel=<n>        " + _("How thorough the block verification is (0-4, default: 3)") + "\n";
     strUsage += "  -txindex               " + _("Maintain a full transaction index (default: 0)") + "\n";
     strUsage += "  -loadblock=<file>      " + _("Imports blocks from external blk000??.dat file") + "\n";
     strUsage += "  -reindex               " + _("Rebuild block chain index from current blk000??.dat files") + "\n";
     strUsage += "  -par=<n>               " + _("Set the number of script verification threads (up to 16, 0 = auto, <0 = leave that many cores free, default: 0)") + "\n";
-
+#ifdef ENABLE_WALLET
+    strUsage += "\n" + _("Wallet options:") + "\n";
+    strUsage += "  -disablewallet         " + _("Do not load the wallet and disable wallet RPC calls") + "\n";
+    strUsage += "  -paytxfee=<amt>        " + _("Fee per kB to add to transactions you send") + "\n";
+    strUsage += "  -rescan                " + _("Rescan the block chain for missing wallet transactions") + "\n";
+    strUsage += "  -salvagewallet         " + _("Attempt to recover private keys from a corrupt wallet.dat") + "\n";
+    strUsage += "  -upgradewallet         " + _("Upgrade wallet to latest format") + "\n";
+    strUsage += "  -wallet=<file>         " + _("Specify wallet file (within data directory)") + "\n";
+    strUsage += "  -walletnotify=<cmd>    " + _("Execute command when a wallet transaction changes (%s in cmd is replaced by TxID)") + "\n";
+#endif
     strUsage += "\n" + _("Block creation options:") + "\n";
     strUsage += "  -blockminsize=<n>      " + _("Set minimum block size in bytes (default: 0)") + "\n";
     strUsage += "  -blockmaxsize=<n>      " + strprintf(_("Set maximum block size in bytes (default: %d)"), DEFAULT_BLOCK_MAX_SIZE) + "\n";