hide calendar & add automatic updates patches

[tioduke]

I wrote two patches for your eventcalendar applet:

1. The first one makes it possible to hide the calendar view (I personally use only the agenda view with the option to show weather icons).
2. The second one adds the possibility of automatic updating the applet over a period of time (polling interval).

If you like them both (or any one of them), please consider merging this pull request to your branch. I am open to any discussion regarding this pull request.

Thank you and best regards.

Sergio (a.k.a TioDuke)

[Zren]

• If we can toggle the calendar, we should also be able to toggle the agenda. I can add that though. I need to add a new state to the grid anyways when either the agenda or calendar is disabled to make it a 1 column grid with __ rows.
• I'll probably change the config text to "Refresh events every [20 minutes]", and move it to... either the calendar tab or google calendar. Right now it's above the version number which is a bad place for it.
• Quota wise, I'm wondering if polling 24h/20min times more than usual will have an effect. I used to have it update whenever the popup appeared but got annoyed with that. Polling is pretty critical for a desktop widget though, so I'll definitely merge this.

For future reference, this is the current GCal API usage:

Edit: I should note that GCal has a 1million requests / day quota, so it's needless worries. OWM has 60 requests / min, which is more likely to be hit.

Note: update() won't actually update the weather unless the hour has changed, this is fine though.

60min intervals * 60 users / 2 requests (daily + 3h meteogram data) = 60x30 = Maximum of 1800 users, assuming they're spread out evenly which won't be the case.

[tioduke]

Thank you for merging. I agree with what you said about changing the "polling" option text and placement: I don't like it where it is now, above current version. Where do you want to put it? I can do the changes for you and make a pull request afterwards, in order to help you out a little. However, I am afraid that putting it under Calendar or Google calendar tabs will lead to the impression that it is only for updating anyone of those. Maybe some other place in the General tab, in its own section?
Best regards.

[Zren]

I kind of want to have a second timer / polling interval for the weather, which can be put in the weather tab since weather won't actually update in smaller intervals than an hour.