every and each unmounting...

`every` makes sense, as the timer will keep running for ever. But should any `each` timer that is still running when things unmount also be unmounted? Note that Observable includes AutoUnmount, so any store will get this behavior as well!

Then, on the other hand, there is an each! and every! method (they don't auto start, so you have to say each!(x).start. Neither of these timers IS auto-unmounted.

Couple of options:

1. just take after out of unmount, and forgettabout it.
2. 1 + provide a remove_after_timers method callable in Observable
3. leave it, and if you want a timer that isn't unmounted use the bang variation.
4. provide auto_unmount(x) attached to the timers so you say: `after(12).auto_unmount(true)` or `every(12).auto_unmount(false)` to override the defaults.

Currently I think its best to make both every and every! behave the same, and make each and each! not autounmount, and then add the `auto_unmount` method to the Browser::Interval and Browser::Delay classes.

```ruby
attr_accessor :mount_point

def auto_unmount(yes)
# warning message and return if mount_point is nil
if yes
AutoUnmount.objects_to_unmount[mount_point] << self
else
AutoUnmount.objects_to_unmount[mount_point].delete(self)
end
end

alias unmount abort
```

now all the automounter does is set mount_point

```ruby
def every!(*args, &block)
super.tap do |id|
next id if unmounted?
id.mount_point = self
id.auto_unmount(true)
end
end
def after!(*args, &block)
super.tap { |id| id.mount_point = self unless unmounted? }
end
```