Before it would only reload if the size changed and even that was
reliable since the method relied on the order of the monitor list.
Now if the monitor list differs in any way (pos, dimension, primary,
output, name) a reload is issued
Removing monitors is not really necessary when selecting the monitor
where to render the bar or choosing the backlight. Since both monitors
occupy the same coordinates rendering can be done on both and it's
better to give people felxibility for the backlight.
Fixes#1191
Premature optimization that tried to cache monitors but the cache did
not take into account the parameter values.
The call `get_monitors(..., ..., false, true);` would get all connected
and unconncected monitors a subsequent call
`get_monitors(..., ..., true, false);` would get back the same list of
monitors even though it requested only connected monitors.
Additionally `get_monitors` is never called periodically so the
optimization really didn't help much.
