Add warning about expire and redesign warning/error popup

Fixes Github Issue #38

src/blackconfig/buildconfig.cpp

@@ -97,6 +97,11 @@ namespace BlackConfig
         return QDateTime::currentDateTime() > getEol();
     }
 
+    int CBuildConfig::daysTillLifetimeExpiry()
+    {
+        return QDateTime::currentDateTime().daysTo(getEol());
+    }
+
     const QString boolToYesNo(bool v)
     {
         return v ? QStringLiteral("yes") : QStringLiteral("no");

src/blackconfig/buildconfig.h

@@ -109,6 +109,9 @@ namespace BlackConfig
         //! Lifetime ended?
         static bool isLifetimeExpired();
 
+        //! Days till lifetime end
+        static int daysTillLifetimeExpiry();
+
         //! Vatsim client id
         static int vatsimClientId(); // defined in buildconfig_gen.cpp.in