Delete removes the current key/value pair the cursor is at without invalidating the cursor.

The interface contract guarantees at least the following errors will be returned (other implementation-specific errors are possible):

- ErrIncompatibleValue if attempted when the cursor points to a
  nested bucket
- ErrTxNotWritable if attempted against a read-only transaction
- ErrTxClosed if the transaction has already been closed

Delete is referenced in 2 repositories