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
- fixed conditional import for pep8 checker
- moved the import to a conditional python 3 import instead of a global
  one, since that seems to be the original intent. Addresses #1900
Merge branch 'master' of https://github.com/kivy/kivy
Merge remote-tracking branch 'upstream/master'
Make mouse simulated mutli-touch optional.
Add docs, only provide sim if initiated so.
Make scatter always use simulated multitouch.
Don't overwrite previous profile.
fix for #2129
Add config callback to change the log file when the config log_dir/log_name change.
Create log_dir path directories recursively

This change will create the custom log folder and its parents, if needed, in the case of using absolute paths too.
Change image pygmae to use file handles instead of path because of unicode issues.