It is now possible to search a contact in the list thanks to the search text edit.
It is also possible to search contacts by category.

When a category is selected, the search text edit only works in the particular category.

A problem has been identified: The categories are entered in Akonadi as String.
It will be a problem when the language will change.
A code will be certainly made to go through.

It is now possible to export contacts in vcard format.
The save file dialog window must be modified to enter in little Screens.
Now the export button is on the main window, but it will certainly be transfered to options/config.