fix #3823: detect import file type by content
avoid NPE on CI

Funny enough, locally that same exception does not happen.
#3818: enable memory dumps on demand
some formatting fixes
Fixes #3838, All caches are "own" if not logged in to GC.com

- check for empty user name in owner check for oc and gc
#3818: remove further GC blocking references
Update changelog_master.xml
Implement ActionBar using AppCompat in cgeo

This a first version of an ActionBar implementation with following properties:

- The application should be usuable (there still might be bugs left from the conversation to Action)
  - Provides a more modern feeling on all devices
  - gets rid of the "dots of shame" on Android 3.0+ devices
- The Maps classes MUST inherit from Activity instead of ActionBarActivity. There these classes use the old ActionBar on Android 2.3 devices and the real ActionBar on 3.0+
   - This can be fixed when cgeo is ported to Google Maps API v2.0 API which usesFragment
- The Dialog classes (CachePopup and WaypointPopup) have been converted to DialogFragments
  - The AppCombat themes provide no Theme.Dialog theme
  - this will later ease using these Fragment in other Activities
  - Use an almost empty activity which just shows the DialogFragment
  - Use the 'old' ActionBar but which overflow menu button to fit into Holo Design Style
  - Using a real ActionBar for Dialogs is not really support by Android and trying to force the frame into showing an Actionbar on a dialog leeds to strange bugs/effects
- Most of the icon are still the Android 2.3 Menu Icon. These need to be replaced with Holo Style Icons
- for most menu icon the ifRoom and/or withText attributes should be reviewed and set
- The ActionBar of the main Activity is transparent. This is more or less by accident but looks good
- Review Up Action of activities. Is going back to Main Activity always the semantically right thing to do?
- Shortpress/Longpress on the Actionbars Compass Icon for primary/secondary Navigation clashes the normal ActionBar behaviour of long pressing to show the text of the action

This commit contains many fixes and suggestions from rsudev
Update menu icons with newer version imported from Android Open Source Project

These menu icon are designed for the new ActionBar
Add off image for the mylocation png and add use for mapsview
Allow the user to choose always displaying the overflow button

Manually Cherry pick from rsudev/actionbar_schwabe: Always display the overflow menu button.

Allow user to decide if the overflow should be shown or not. Since this
only works on 3.0-4.3 hide the option on other platforms.
Remove conflicting lib