Undefined constant USERPOINTS_KARMA_POINTS_VOTER_CHANGE

In userpoints_karma.module, the constant USERPOINTS_KARMA_POINTS_VOTER_CHANGE is referenced but is not defined anywhere. This throws PHP warnings, and results in the Drupal system variable being all-caps (unlike the rest of this module's variables).

Please add something like this near the top of userpoints_karma.module:

define('USERPOINTS_KARMA_POINTS_VOTER_CHANGE', 'userpoints_karma_points_voter_change');