Don't choke on proxy detection if allow_offline = true.

This unfortunately relies on _app.init() happening *inside* detect proxy in the
particular code path that results in failed proxy detection. I wish app.init
wasn't such a twisty maze of spaghetti, but that ship has long since sailed.

src/main/java/com/threerings/getdown/data/Application.java

@@ -829,6 +829,14 @@ public class Application
         return _optimumJvmArgs != null;
     }
 
+    /**
+     * Returns true if the app should attempt to run even if we have no Internet connection.
+     */
+    public boolean allowOffline ()
+    {
+        return _allowOffline;
+    }
+
     /**
      * Attempts to redownload the <code>getdown.txt</code> file based on information parsed from a
      * previous call to {@link #init}.

src/main/java/com/threerings/getdown/launcher/Getdown.java

@@ -162,7 +162,9 @@ public abstract class Getdown extends Thread
 
         try {
             _dead = false;
-            if (detectProxy()) {
+            // if we fail to detect a proxy, but we're allowed to run offline, then go ahead and
+            // run the app anyway because we're prepared to cope with not being able to update
+            if (detectProxy() || _app.allowOffline()) {
                 getdown();
             } else if (_silent) {
                 log.warning("Need a proxy, but we don't want to bother anyone.  Exiting.");