Fix icon reference by position instead of key

Introduced by mistake in 18bc0aac .
Activity palette: remove space in label Description
Move all initial configuration to activity.setup

And set colors to the icon at the top of the activity palette.
Fix palette variable from global to local inside palette module

All these should be declared with 'var', otherwise they are global.
Improve ActivityPalette API
Improve width of palettes

- minimun width of 3 cells
- maximun width of 5 cells
Style palette rows and activity palette