Servers with open_basedir will likely fail on /etc accesses

This is no problem, but it creates an error message even for
file_exists(). Silence it.
(CDB) Fix some small tooltip bugs
Merge pull request #11 from pgeorgi/etc-fix

Servers with open_basedir will likely fail on /etc accesses
(Core) GetScript now accept parameters in url
Fix some bugs through changes in jQuery 10.2
Change remember login time from 7 to 6 days
(CDB) Group statistics is now viewable for ordinary group leaders
Mention changes in the CHANGELOG.txt
Optimize dialogs for iOS
(CS) Optimizations for iPad
(CW) Bugfix problem when saving empty wiki pages
(CDB) Groupleaders now only see "delete tasks" if they are allowed to delete people from the group
(CDB) Bugfix group filter only when selecting groupmembertype
Add OpenLayers 2.13.1
Use OpenLayers for map views

And the OSM nominatim service for geocoding, and the OSM default map.
Split overlay in person and group layer

Also fix up the OpenLayers design a bit
Make Google Maps use optional

The default is GMaps, but the example config sets up OSM.
In case no Google Maps are used, its javascript isn't loaded either.
Maps rework

- remove the person/group buttons.
  Instead, these are now separate layers

- make person layer a vector layer
  This allows collecting clusters of people
  into a single item with a counter

- hide some maps internals
Add addPersons interface to maps

This allows preparing a large set of persons to add in one go,
which performs much better on large data sets (eg. 10k entries)
Make sure dialogs are on top

Sometimes some OSM elements would sneak in front of jquery dialogs