fix HKU/HKCU root key parsing

[tothi]

examples/reg.py incorrectly parsed HKU root key for Current User, fixed it to User, and added HKCU for Current User.

[mubix]

The HKU -> HKCU fix to HKU->HKU fix you have here just saved me multiple hundreds of hours of banging my head against the wall in MSDN trying to figure out why I wasn't getting SIDs. Thank you @tothi - hope this fix gets merged soon.

[dadevel]

The fix for HKU/HKCU was merged with #1638.