sdl2: start to write a new window provider based on sdl2. sdl2.pxi has been created from the ignifuga game engine, but maybe functions and definitions are missing. Need to create a generator out of it. At some points, window_sdl (used currently only on iOS) should be removed.)
sdl2: add missing window_sdl2 files, and correctly implement 'auto' fullscreen. read all the missing window event too.
sdl2: add sdl2 image core provider (not complete, need more conversion format, and save support)
sdl2: support for text rendering
sdl2: ignore generated .c
sdl2: fix ignore
sdl2/text: fix color bgra -> rgba
core:sdl2 clipboard provider
Bring sdl2 in line with current master and other fixes to make things usable. Sponsored by ScramSoft.
Merge branch 'master' of http://github.com/kivy/kivy into sdl2-support

Conflicts:
	.gitignore
	doc/sources/faq.rst
	doc/sources/guide/android.rst
	examples/audio/audio.kv
	examples/audio/main.py
	kivy/_event.pyx
	kivy/adapters/__init__.py
	kivy/adapters/adapter.py
	kivy/config.py
	kivy/core/clipboard/__init__.py
	kivy/core/image/img_imageio.pyx
	kivy/core/image/img_pil.py
	kivy/core/video/video_ffpyplayer.py
	kivy/core/video/video_gi.py
	kivy/core/video/video_gstplayer.py
	kivy/core/video/video_pygst.py
	kivy/core/window/__init__.py
	kivy/event.py
	kivy/graphics/common.pxi
	kivy/graphics/texture.pyx
	kivy/graphics/vertex_instructions.pyx
	kivy/graphics/vertex_instructions_line.pxi
	kivy/input/providers/androidjoystick.py
	kivy/input/providers/mouse.py
	kivy/lib/gstplayer/_gstplayer.pyx
	kivy/network/urlrequest.py
	kivy/properties.pyx
	kivy/tools/packaging/win32/kivy-2.7.bat
	kivy/tools/packaging/win32/kivy-3.3.bat
	kivy/tools/packaging/win32/kivy.bat
	kivy/uix/behaviors.py
	kivy/uix/checkbox.py
	kivy/uix/codeinput.py
	kivy/uix/dropdown.py
	kivy/uix/listview.py
	kivy/uix/screenmanager.py
	kivy/uix/scrollview.py
	kivy/uix/textinput.py
	kivy/uix/vkeyboard.py
	kivy/uix/widget.py
	kivy/utils.py
	setup.py
fix leftover conflicts from last merge
Merge pull request #2488 from kivy/sdl2-support

Sdl2 support