uix:ActionBar make items added to ActionOverflow persistant in the
overflow dropdown. Minor bug fixes.
uix:Settings fix handeling of numeric input, no body had a issue with
this??
doc: added some explanation to AsyncImage to completeness
uix:ActionBar fix group_index to be calculated after all groups have
been added
uix:ActionBar allow changing of proeprties like color, mipmap, border
through the ActionItem.
uix:TabbedPanel introduce new `strip_image` and `strip_border`
properties that can be used to easily  customize Tab strip.
doc: revisions to ext/__init__.py
doc: revisions to input/factory.py
doc: revisions to input/__init__.py
Solved issue #1388 where ``lang._handlers`` keeps widgets alive.

The original problem was caused by 2 things: 1) during
``create_handler``, in the binding clause, we did not make sure that
``f`` is a weak proxy. 2) during template creation, the ``ctx``
dictionary is passed in as is, instead of making sure to use only the
weak proxies of the corresponding widgets in the dictionary.
Merge remote-tracking branch 'kivy/master' into lang_handler_memory_leak_fix
New german QWERTZ keyboard layout
simultaneous system and virtual keyboard input
Merge branch 'master' of https://github.com/kivy/kivy into dual-keyboard-mode
Merge pull request #1404 from rentouch/dual-keyboard-mode

Dual keyboard mode & New german keyboard
config: add versionchanged for systemanddock and systemandmulti values to keyboard_mode
Merge pull request #1402 from kivy/tabbed_panel_strip

uix:TabbedPanel introduce new `strip_image` and `strip_border`
Merge pull request #1399 from kivy/action_overflow

uix:ActionBar make items added to ActionOverflow persistant in the overflow dropdown. Minor bug fixes.
Merge pull request #1398 from kivy/numeric_settings

uix:Settings fix handeling of numeric input
core: fix remaining basestring left in the code