Gives category Spinner an ID

Without an ID, the default save/restore state mechanism doesn't work,
so (for example) if you rotate the screen on ICS, the current category
switches back to the default.

res/values/ids.xml

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+  <item type="id" name="categorySpinner" />
+</resources>

src/org/fdroid/fdroid/FDroid.java

@@ -298,6 +298,9 @@ public class FDroid extends TabActivity implements OnItemClickListener,
                 LinearLayout v = new LinearLayout(FDroid.this);
                 v.setOrientation(LinearLayout.VERTICAL);
                 Spinner cats = new Spinner(FDroid.this);
+                // Giving it an ID lets the default save/restore state
+                // functionality do its stuff.
+                cats.setId(R.id.categorySpinner);
                 cats.setAdapter(categories);
                 cats.setOnItemSelectedListener(FDroid.this);
                 v.addView(cats, new LayoutParams(