hook_diff() has been replaced with hook_entity_diff()
many new field hooks and callbacks have been added
system variable names have been changed so that they are entity specific and also that they are prefixed with "diff_"
Diff 7.x-2.0+13-dev to Diff 7.x-3.0-alpha1
o #888680 by Deciphered, Alan D.: Allow modules to interact via drupal_alter()
o #1280892 by Alan D., crea: Diff should track the variables that it defines
o #1304658 by Alan D., kari.kaariainen: Remove links and comments from the comparison preview
o #1122206 by binford2k, Alan D.: Notices thrown by DiffEngine::process_chunk()
o #1175064 by zilverdistel, Alan D.: Provide variables for leading and trailing context
o #1673864 by Alan D.: Allow users to bypass the admin theme when viewing comparisons
o #1673876 by Alan D.: Use Drupal autoloading for classes
o #1673856 by Alan D.: Use hook_form_BASE_FORM_ID_alter() rather than hook_form_alter()