ui: Fix GUI initialization order

Fixes at least #3478.

Splits and documents the phases:
1. Parse command-line options. These take precedence over anything else.
2. Basic Qt initialization (not dependent on parameters or configuration)
3. Application identification
4. Initialization of translations
5. Now that settings and translations are available, ask user for data directory
6. Determine availability of data directory and parse bitcoin.conf
7. URI IPC sending
8. Main GUI initialization

Splits command line parsing logic from ipcSendCommandLine into
ipcParseCommandLine, as isTestNet() can only be overridden in the early
stages before choosing a data directory. Sending however needs to happen
after choosing a data directory.

src/qt/paymentserver.cpp

@@ -180,10 +180,8 @@ void PaymentServer::LoadRootCAs(X509_STORE* _store)
 // and the items in savedPaymentRequest will be handled
 // when uiReady() is called.
 //
-bool PaymentServer::ipcSendCommandLine(int argc, char* argv[])
+bool PaymentServer::ipcParseCommandLine(int argc, char* argv[])
 {
-    bool fResult = false;
-
     for (int i = 1; i < argc; i++)
     {
         QString arg(argv[i]);
@@ -226,7 +224,18 @@ bool PaymentServer::ipcSendCommandLine(int argc, char* argv[])
             qDebug() << "PaymentServer::ipcSendCommandLine : Payment request file does not exist: " << arg;
         }
     }
+    return true;
+}
 
+//
+// Sending to the server is done synchronously, at startup.
+// If the server isn't already running, startup continues,
+// and the items in savedPaymentRequest will be handled
+// when uiReady() is called.
+//
+bool PaymentServer::ipcSendCommandLine()
+{
+    bool fResult = false;
     foreach (const QString& r, savedPaymentRequests)
     {
         QLocalSocket* socket = new QLocalSocket();