Fixes incorrect link reported in https://github.com/kivy/kivy/issues/712
Added section titles that spell out which files the code and layout go in.
I got a little lost working through this example because I made an incorrect assumption about the filename needed for controller.kv. The goal to this change is to draw more attention to the filename and keep future users from making the same mistake.
fix #731 BoundedNumericProperty can have float bounds
make python version requirement clearer
fix for slider bug when min<0, max>0 and step>0
Merge pull request #736 from Titousensei/fix_slider

fix for slider bug when min<0, max>0 and step>0
:UIX:TabbedPanel: ensure tab_strip width is updates withtab's width
UIX:TabbedPanel: ensure unbind to avoid multiple binds for tab
width/height
Merge pull request #733 from kivy/fix_731

fix #731 BoundedNumericProperty can have float bounds
Merge pull request #715 from edthedev/design_guide_larger_filenames

Design guide larger filenames
doc: fix pyinstaller instructions for Windows
fix pdf generation
Update kivy/lang.py

typo in the doc
Merge pull request #744 from bibile/patch-1

Update kivy/lang.py
Add a new showcase example that allows interactive editing of Kivy language code to see how it affects the widgets.
class decorators are so much sexier than meta classes
Add a keybinding to the Kivy textarea to render when ctrl-S is pressed.
Update the more or less pathetic help screen.
Switch to a screen manager for better use of screen real estate
Fix bugs in scatter demo