* Rename TSQueryContext -> TSQueryCursor
* Remove the permanent association between the cursor and its query. The
cursor can now be used again for a different query.
This binary search implementation differs from Rust's
`slice::binary_search_by` method in how they deal with ties.
In Rust's implementation:
> If there are multiple matches, then any one of the matches
> could be returned.
This implementation needs to return the index of the *first* match.
