Hint label collision

[edralston]

When there are a mixture of one-character and two-character hint labels, occasionally one or more of the two-character hint labels will start with the same character as one of the one-character hint labels, making it impossible to select the one-character hint label. For example, the set of hint labels might contain "j" and "ja" and "jb" and "jc" but in this case, it would be impossible to select the object associated with hint label "j" since the hint engine will still be attempting to match against "ja" or "jb" etc.

Addressed by @edralston in https://github.com/raphamorim/rio/pull/1289