Update Warning-strings to use a standard-format

- ensure warnings always start with "Warning:" and that the first
  character after ":" is written uppercase
- ensure the first sentence in warnings ends with an "!"
- remove unneeded spaces from Warning-strings
- add missing Warning-string translation
- remove a "\n" and replace with untranslatable "<br><br>"

src/net.cpp

@@ -589,7 +589,7 @@ bool CNode::Misbehaving(int howmuch)
 {
     if (addr.IsLocal())
     {
-        printf("Warning: local node %s misbehaving (delta: %d)\n", addrName.c_str(), howmuch);
+        printf("Warning: Local node %s misbehaving (delta: %d)!\n", addrName.c_str(), howmuch);
         return false;
     }
 
@@ -812,7 +812,7 @@ void ThreadSocketHandler2(void* parg)
 
             if (hSocket != INVALID_SOCKET)
                 if (!addr.SetSockAddr((const struct sockaddr*)&sockaddr))
-                    printf("warning: unknown socket family\n");
+                    printf("Warning: Unknown socket family\n");
 
             {
                 LOCK(cs_vNodes);