separate update-interval's for extended Vehicle & Meter data

- ext_meter & ext_veh data disabled by default

- default update-interval to 60 seconds
- added "warning" text for ext_veh data

possible fix for #279

added 'smartFeedInPriorityLimit' & 'smartFeedInPriorityActive'

fix #276

fix update interval for config data (was always 15minutes)

refactored meter-'sensor' enabale/disable detection

messed up defaults (for new options)

force device refresh when extended vehicle/meter settings change

IMHO fine check if entities should be disabled based on data availabi…

…lity from evcc