The construction of an EventHandler object should not be directly done
by the client. Instead, it is easier to use procedural macro to
automatize the process, hence exposing a nice and simple interface. Such
use of procedural macros requires to crate an additional crate.
The previous design did not handled errors correctly and was kind of
spaghetti code. With the new one, the reader and the dispatcher are
clearly separated. The filter will only exit on an error from the reader
or if EOF has been reached, any other error is displayed but does not
exit the filter, which is required by the API. If the filter must exit,
all threads are gracefully stopped.
