integrated AnkiStats project in AnkiDroid, updated libAnki Stats class with new functions
Manifest with new Activity entry for new statistics
removed bitmap processing and switched to new custom view for statistics,
combined all 8 statistics chartbuilder classes in one and removed redundancy
reverted to normal CustomExceptionHandler
fixed Answer Buttons statistics for deck life and non whole collections setting,
fixed statistics for decks with no activity in selected time frame freezing app due to infinite loops on ui thread caused by x- or y-start and -end values beeing the same
added licence header to new files, adjusted drawing of bar graph to prevent washed out effect from anti-aliasing
reverted to int for type to follow libanki guidlines
Merge pull request #422 from trashcutter/new_stats

New statistics to include all graphs from Anki-Desktop