accessibility patterns and aria

[gpicavet]

Hello,
It appears several components dont expose ARIA roles and behave not very well with keyboard and assistive technologies.
I propose to follow these simple patterns :

• give correct aria role on non-native components (like dialog, alert, etc...)
• allowing keyboard navigation and actions (user should navigate with arrows inside a component, with tab in a form, activate a link/button with space ou enter, cancel with ESC)
• trap keyboard focus in a modal dialog and reposition focus to the button that trigged the dialog when closing it.
• animations-less mode

[hai-cea]

Thanks @Grisha78

Yes, this is something that's really important to us. Please see #61