This fixes a NullPointerException that would occur when restoring from
savedInstanceState due to getSupportActionBar returning null. It also removes
the theme definitions from AndroidManifest as we override those anyway.
This fixes the following bugs:
- Sort category is forgotten after lock/unlock
- The sort mode is not respected for new entries
I got a little carried away while working on this patch and also included the
following other enhancements:
- Simplify the SortCategory, Theme and ViewMode enums
- Simplify usage of string resources
- Don't call notifyDataSetChanged and runLayoutAnimation unnecessarily