olc_get()

[Quinlan Pfiffer]

Currently there is no clear way to get the value of a cursor's current_node. Ideally on olc_step or olc_step_back, we would unjar the data into a cursor->data pointer which would hold this data until you step again. We would need to bring olc_close back to clean up this data.

This ticket entails:

• Add new functions: olc_get(ol_cursor *cursor, unsigned char **data), olc_close(ol_cursor *cursor)
• Change tests to handle this new functionality
• Modifying the ol_cursor struct
• Modifying existing cursor iteration code to use this function