static memory alternative for std::function

[MatthiasKillat]

Brief feature description

We need an alternative to std::function as a owning generic function wrapper. This alternative should

• not use dynamic memory (or make this optional/configurable)
• not employ virtual functions
• own all data to execute the callable
• be compatible with functors (lambdas) and function pointers

Detailed information

This is needed to store callables without using dynamic memory as in std::function.
Internal virtual function calls are not allowed if we want to store these callables in shared memory.

This can potentially help to resolve #131, but here it may not be needed (using function_ref may be sufficient). Nevertheless an owning wrapper compatible with our constraints would be useful in future software design.