duplicate values

[chaals]

The HTML 4 and HTML5 specifications do not explain what to do if the same accesskey value is used for two different elements. Since this does happen, that should be fixed.

[chaals]

The proposal now allows explicitly for duplicate values, but doesn't yet say what browsers should do with them.

[chaals]

Where there are different objects with the same value, I will suggest the current IE behaviour, which is to cycle focus between them as the shortcut is repeatedly used.

See also #15