Fix issue #2448075: aapt doesn't fix up activity-alias android:targetActivity links

And related:

- The aapt tool now sets a resource configurations sdk level to match any configs
  that have been set (for example if you specify density your sdk level will be
  at least 4).
- New option to modify the targetPackage attribute of instrumentation.
- Clean up of aapt options help.
- Fix of UI type values to leave 0 for "unspecified".
- Make the UI mode config APIs public.