Fixes #750: New Settings Screen

* before testing, backup your prefs. You can't go back to a version without the new preferences dialog. I had to migrate some preferences.
* The old settings dialog still exists. Just some texts are changed. This I will switch off when we are done discussing this PR.
* Info text for geocaching.com appears when gc.com is activated (checkbox). This is one possible approach.
* New: slider for waypoints threshold. values: 0 to 50
* Info text for offline maps and themes changed - now in popup dialog
* removed: submenu in old settings to reset login data. Either deactivate a service or remove password of GcVote
* titlebar: settings cannot be embedded in another layout (with cgeo titlebar). A good looking title bar comes with the usage of ActionBarSherlock
* preference category titles (e.g. "standard navigation" in "More Settings"): I think these should be styled to be more distinguishable. The problem is all the other small text around some headers. It looks quite chaotic. But the small texts are necessary, I think.
* someone has to test it on a tablet. I absolutely don't know how that looks on a large screen. Can't test it, my laptop is too slow for some Android versions in the emulators
* screen rotation magically works out of the box
* translations: the old checkboxes had a rather long text. Now these text are displayed in small font unter the regarding preference (it's called summary). For all languages except de and en the preferfences big text and the summary both have the long text. See here: https://www.dropbox.com/sh/73jjxbzprxa5qve/Ectuuo5OJR/Screenshot_2013-06-30-11-01-05.png
* how do I make 1 commit out of these 7 commits?

some preview shots: https://www.dropbox.com/sh/73jjxbzprxa5qve/WDFl6u0IPA