load extensions before preloading components to have aliases set for
extensions like debug module.

- allows to have dynamic definition of attributes depended on the
  instance
- there was no real need for it to be static. Places that used it static
  have been refactored.

fixes #1318

avoid XSS with emails in format  "Carsten Brandt <mail@cebe.cc>"

- added example code for application components
- added missing short description

[ci skip]