Fix daemonize for Windows

Fixes #1034

src/bitmessagemain.py

@@ -316,13 +316,23 @@ class Main:
             BMConfigParser().remove_option('bitmessagesettings', 'dontconnect')
 
     def daemonize(self):
+        try:
             if os.fork():
                 exit(0)
+        except AttributeError:
+            # fork not implemented
+            pass
+        else:
             shared.thisapp.lock() # relock
         os.umask(0)
         os.setsid()
+        try:
             if os.fork():
                 exit(0)
+        except AttributeError:
+            # fork not implemented
+            pass
+        else:
             shared.thisapp.lock() # relock
         shared.thisapp.lockPid = None # indicate we're the final child
         sys.stdout.flush()