bugfix: exc. on refresh when gpodder.net not run

exception handling added
Switch to Theme.Holo.
Removed one log line in buffering
README.md: Issue report infos
Modified Logo with Stronger Outlines
Add a spinning gear to the refresh button

The progress dialog can now be dismissed, but the spinning gear will remain
until the sync is complete or fails. Pressing the refresh button during an
ongoing refresh displays the progress dialog again so the user can see what
is going on.
Debugging output for handler null reference issue
Fix compilation failures caused by nonpublic interfaces
Bug #17272 again, maybe this time it's over
Remove lots of redundant code
Renamed "All Podcasts" to "All Episodes"
Changed "All Podcasts" to "Show All Episodes"

+ icon, now it looks nearly like a "normal" podcast, but it should still
be clear for the user
Tried to implement "Add Podcast From URL"

But does not work, GPodder doesn't parse podcasts that are not previously
known anyway.
Added add podcast from URL
Remove the CallbackContainer and use callbacks directly
A few checks in add URL
Reverted DB Podcast to version 12
Cleanup of add podcast from URL
Fix test cases once again

1. a test case referred to an old deleted icon
2. a test case referred to a nonexistent test mp3
3. the test interface was not updated with with changes to the main
project
Removed dataVersion from Podcast object