event/properties: when a static value has been detected for a unexisting property, instead of creating ObjectProperty, check either if we can use a String/Numeric/List property
event: add DictProperty, and add documentation of the changes
lang/properties: add documentation about default properties values / type specialization. closes #1519
Merge branch 'fix-1519'
event: fix create_property documentation
Merge branch 'master' of ssh://github.com/kivy/kivy