Add account to joins for the log module.

This commit adds the account name for identified users to "Joins" lines in logs
generated by the log module.  It can get the account name from either the
account tag (if the account-tag capability is requested) or the extended-join
info (if the extended-join capability is requested).  The current version of ZNC
requests both, but this feature will still work if the IRC server only supports
one or the other.

modules/log.cpp

@@ -99,7 +99,7 @@ class CLogMod : public CModule {
                 const CString& sMessage) override;
     void OnQuit(const CNick& Nick, const CString& sMessage,
                 const vector<CChan*>& vChans) override;
-    void OnJoin(const CNick& Nick, CChan& Channel) override;
+    void OnJoinMessage(CJoinMessage& Message) override;
     void OnPart(const CNick& Nick, CChan& Channel,
                 const CString& sMessage) override;
     void OnNick(const CNick& OldNick, const CString& sNewNick,
@@ -457,12 +457,26 @@ CModule::EModRet CLogMod::OnSendToIRCMessage(CMessage& Message) {
     return CONTINUE;
 }
 
-void CLogMod::OnJoin(const CNick& Nick, CChan& Channel) {
-    if (NeedJoins()) {
-        PutLog("*** Joins: " + Nick.GetNick() + " (" + Nick.GetIdent() + "@" +
-                   Nick.GetHost() + ")",
-               Channel);
+void CLogMod::OnJoinMessage(CJoinMessage& Message) {
+    if (!NeedJoins())
+        return;
+
+    const CNick& Nick = Message.GetNick();
+    CChan& Channel = *Message.GetChan();
+    CString Account = Message.GetTag("account");
+    const char* s = " ";
+
+    if (Account.empty())
+        Account = Message.GetParam(1);
+
+    if (Account.empty() || Account == "*") {
+        Account = "";
+        s = "";
     }
+
+    PutLog("*** Joins: " + Nick.GetNick() + " (" + Nick.GetIdent() + "@" +
+           Nick.GetHost() + ")" + s + Account,
+           Channel);
 }
 
 void CLogMod::OnPart(const CNick& Nick, CChan& Channel,