Changes and additions:
Preferences page:
- add library
- git account
- manage library

Attribute:
- add add attribute wizard

Behavior wizard
- add edit function
- add "add code" function (not completed yet)

To do:
- edit and delete attribute
- fixing "add code" function
- add edit functionality to component wizard
Fix: edit attribute, edit component
add delete attribute and delete behavior in component detail wizard
add "behaviortree.common"