optimized tab-order, fixed stylesheet, fixed CKEditor (FFOX).

Fixes:
- editing notes works in Firefox again (without RTE-CKEditor)

Features:
- optimized tab-order in input-area (tag input field before submit field)
- fixed stylehseet for UNDER_THE_TOP-Notification dialog

Pending:
- current layout currently does explicitly not support IE9, IE10 and Opera
- mathjax-formula preview

Documentation:
https://www.eduzen.tu-berlin.de/software-komponenten (German)
https://www.eduzen.tu-berlin.de/zur-notizen-webanwendung (German / Get User Account)