Show RTT measured by ICMP echo request/replies for a given host.
For that to work correctly, change the "full_text" callback for a widget
so that the widget itself is also passed as argument in the callback
method. That actually makes a lot of sense, since the widget can now be
used as a repository of state information.
see #23
This is going to be a bit more comprehensive than anticipated. In order
to cleanly refactor the core and the engine, basically start from
scratch with the implementation.
Goals:
* Test coverage
* Maintain backwards compatibility with module interface as much as
possible (but still make modules easier to code)
* Simplicity
see #23
Hide alias concept for modules in the engine. That way, the individual
modules never get to know about whether a module has been aliased or
not.
see #23
Due to a bug, when the destination was unreachable, the checking thread
would terminate, effectively keeping the widget stuck in "unreachable"
mode.
Now, enable recovery by keeping the thread running even if the target is
not reachable for some time.
