add short flash effect

[s-light]

add some sort of 'light-burst' / flash effect.

evenutaly for this effect it would make sens to reconfigure constant-current driver settings!
→ be careful: this could lead to very high heat-sink temperatures - so this should be only possible in controlled intervals to let cool of things in between..

sketch:
first sparkles - they get brighter and brighter - then very fast ramp up to full brightness -
and then a slower fade-down back to smooth default animation