Directory format

[andreafioraldi]

We have entities (eg executor) and for each entity we will provide some implementations into libafl (eg inmemoryexecutor and forkserverexecutor). These implementations are part of the library, they should not be in the example folder.

I propose to create a subfolder in include and src for each entity and place into them a main file with the asbtract class and the other implementations.

For instance.

include/executor/executor.h contains only the abstract class
include/executor/in_memory_executor.h contains the implementation

same for src/

Btw just look at FFF