I see some things that may help you improve your code.
Don't leak memory
I see that there are a number of places in which new is invoked but there is no corresponding delete. For example, one leak can be addressed by adding this destructor:
Put friend declarations in public section
Nice, well-presented code, apart from some spacing inconsistency following for, if etc.
I think the Cell constructor should be explicit. It's odd that it's missing initializers for the timers (I use gcc -Weffc++, so tend to include them even for types that won't end up uninitialized).
constexpr auto intervall = 50;
would be better named interval.