Establishing that Handsontable meets the accessibility standards

[aninde]

Description

This issue will include a plan to test accessibility in the Handsontable

Requirements

1. "Web Content Accessibility Guidelines" published by the W3C(r).
2. The regulations of Section 508 of the US Rehabilitation Act, especially Subpart B "Technical Standards" https://www.w3.org/WAI/GL/508/508-UAAG.html
3. German law Barrierefreie Informationstechnik-Verordnung https://www.w3.org/WAI/policies/germany/

Chores

• [ ] developing test cases based on requirements from standards
• [ ] finding a tool
• [ ] writing tests