Use Drawer in Settings app

- get rid of PreferenceActivity as much as we can and use fragments instead
- add Drawer widget
- add Dashboard high level entry into the Drawer (but this is work in progress and would be done in another CL)
- add bypass of fragment's Header  validation when launched from the Drawer but *force* validation if external
call thru an Intent

Be aware that WifiPickerActivity should remain for now a PreferenceActivity. It is used by SetupWizard and should
not trigger running the SettingsActivity's header building code. SetupWizard is a Home during the provisionnig process
and then deactivate itself as a Home but would make the Home header to appear in the Drawer (because momentarily we
would have two Home).

Also, verified that:

- the WiFi settings still work when called from SetupWizard
- when you have multiple Launchers, the Home header will appear in the list of Headers in the Drawer

Change-Id: I407a5e0fdd843ad7615d3d511c416a44e3d97c90

src/com/android/settings/SettingsPreferenceFragment.java

@@ -22,12 +22,9 @@ import android.app.Fragment;
 import android.content.ContentResolver;
 import android.content.Context;
 import android.content.DialogInterface;
-import android.content.Intent;
 import android.content.pm.PackageManager;
-import android.net.Uri;
 import android.os.Bundle;
 import android.preference.Preference;
-import android.preference.PreferenceActivity;
 import android.preference.PreferenceFragment;
 import android.text.TextUtils;
 import android.util.Log;
@@ -305,13 +302,13 @@ public class SettingsPreferenceFragment extends PreferenceFragment implements Di
 
     public boolean startFragment(
             Fragment caller, String fragmentClass, int requestCode, Bundle extras) {
-        if (getActivity() instanceof PreferenceActivity) {
-            PreferenceActivity preferenceActivity = (PreferenceActivity)getActivity();
-            preferenceActivity.startPreferencePanel(fragmentClass, extras,
+        if (getActivity() instanceof SettingsActivity) {
+            SettingsActivity sa = (SettingsActivity) getActivity();
+            sa.startPreferencePanel(fragmentClass, extras,
                     R.string.lock_settings_picker_title, null, caller, requestCode);
             return true;
         } else {
-            Log.w(TAG, "Parent isn't PreferenceActivity, thus there's no way to launch the "
+            Log.w(TAG, "Parent isn't Settings activity, thus there's no way to launch the "
                     + "given Fragment (name: " + fragmentClass + ", requestCode: " + requestCode
                     + ")");
             return false;