Represents how position is "sticking" with neighbour nodes. Used to define how position should be transformed (moved)
in edge cases. Possible values: 'toNone', 'toNext', 'toPrevious'.
Examples:
Insert. Position is at | and nodes are inserted at the same position, marked as ^:
- sticks to none: <p>f^|oo</p> -> <p>fbar|oo</p>
- sticks to next node: <p>f^|oo</p> -> <p>fbar|oo</p>
- sticks to previous node: <p>f|^oo</p> -> <p>f|baroo</p>
Move. Position is at | and range [oo] is moved to position ^:
- sticks to none: <p>f|[oo]</p><p>b^ar</p> -> <p>f|</p><p>booar</p>
- sticks to none: <p>f[oo]|</p><p>b^ar</p> -> <p>f|</p><p>booar</p>
- sticks to next node: <p>f|[oo]</p><p>b^ar</p> -> <p>f</p><p>b|ooar</p>
- sticks to next node: <p>f[oo]|</p><p>b^ar</p> -> <p>f|</p><p>booar</p>
- sticks to previous node: <p>f|[oo]</p><p>b^ar</p> -> <p>f|</p><p>booar</p>
- sticks to previous node: <p>f[oo]|</p><p>b^ar</p> -> <p>f</p><p>boo|ar</p>
