Trebuchet : Add 2 Hotseat preferences

This adds 2 preferences for the hotseat (Launcher main bar)

- Choose the number of icons on the hotseat
- Choose the place of the applications drawer button

- Translations in English + French

This is usefull for big screen devices.
You can set from 1 to 9 buttons on the hotseat.
You can set the app button where you want.
Default values  are keeped unchanged so there is no pb with first screen
tuto + no pb with default shortcuts.