Add missing enum value

[learn-more]

Fixes #208

[coveralls]

Coverage increased (+0.2%) to 55.995% when pulling 72f1362 on learn-more:add_cursor_hand into af62ddf on swistakm:master.

[learn-more]

@swistakm I have another PR lined up that builds on top of this, adding native cursor support for the pyglet backend.
How do you want me to proceed with this, create a new PR for both the pyglet changes and this enum addition, wait for this PR to be merged or something else entirely?

[swistakm]

Sorry it took so long. You can submit your next PR.