• Add : The patchlevel with which the module has been built is now
  exported with the VMG_PERL_PATCHLEVEL constant.
  
• Chg : Version checking macros overhaul.
  
• Fix : 'uvar' magic should only be enabled in maint-5.10 and higher
  since it's never going to be backported to 5.8.
  
• Fix : Likewise, the copy callback API change should only be enabled in
  5.11 and higher.
  
• Fix : Instead of those ackward fake refcount increments in the wizard
  destructor, flag the wizard with SVf_BREAK and force temps
  cleanup. This should fix the wizard destruction for all perls,
  and solves the leak introduced by the previous solution.