issue 2206
issue 2069
Update AndroidManifest.xml

Bump version to 2.3alpha4
Merge pull request #445 from timrae/previewer

Previewer fixes
removed dependencies of old statistics in NavigationDrawerActivity and StudyOptionsFragment, removed achartengine and old CharBuilder class,
added transparency to some statistic graphs, changed "select deck" icon in statistics
removed statistic DeckTask (statistic uses own AsyncTask for now)
fixed crash on reselecting preselected all decks item in statistics deck selection
changed statistic deck and time frame selection to submenu, changed statistics title to deck name (short)
Changed Title of Study Options to Activity name and added Subtitle as short deck name (only selected sub deck), cleaned up AnkiStatsActivity of unnecessary elements
changed submenu to have radio items.
fixed Manifest entries (removed entries for old statistic classes), added attribut 'formatted="false"' to strings that use percent sign.