Implemented inline Search bar functionality - work in progress

- Search bar is shown on groups and entries pages. This was asked by users to improve usability.
Fixed error when opening empty database

- If Keepass database is empty the searchbar should not be shown.
Added show search bar to app settings - work in progress
Added hide/show search to pulley menu - work in progress
Search bar state is now saved in settings
Focus of search bar on app startup will be stored in settings

- New search bar functinality is now implemented and replaces the old search page completely.
- This closes #54.
Merge branch 'searchbar'