Avoid NullPointerExceptions in empty sections

When a section is empty, the result list is omitted from the Json but
the Json result still contains a "limits" element. Thus checking for
result.size() == 0 is not robust enough. So check for the actual list
element to exist.
Handle empty playlists correctly

Do not throw NullPointerExceptions and
IndexOutOfBoundExceptions when retrieving an empty
playlist.
Now playing: Handle duration == -1 in remaining time

Here unknown durations are given as -1, so handle that
when formatting the remaining time.
Merge pull request #90 from frankosterfeld/work/no-duration

Now playing: Handle duration == -1 in remaining time
Merge pull request #89 from frankosterfeld/work/fix-empty-list-npe

Work/fix empty lists/sections
Fix building with ant

Also add the lib-src directory to the sources to compile.
Make widget vertically resizable + add a small version
Allow widget to be used on the lock screen
Add widget preview image
Fixed remote bug (screen rotate = no keyup event)

The button_up event was not being sent to XBMC after a screen rotate.
Also, the timer for setting_send_repeats mode was not canceled after a
screen rotate, causing it to run indefinitely. Fixed by remembering the
current button being pressed, cleaning up the KeyPressTask, and sending
button_up events where appropriate.
Merge pull request #93 from mcuelenaere/fix-ant-build

Fix building with ant
Merge pull request #98 from ajhodges/master

Fixed remote bug (screen rotate = no keyup event)
Merge pull request #94 from mcuelenaere/add-lockscreen-widget

Allow using widget on the lock screen