Scripts/ToC: Twin Val'kyr

- Script rewritten to EventMaps
- Implemented random special ability sequence
- Adjusted timer for special abilities to 45 seconds
- Misc clean up.
Closes #7546

(cherry picked from commit e5da0dccfac75fc1ccb111b9977f31ff35745922)
Scripts/ToC: Few codestyle changes and clean ups

(cherry picked from commit f6896c9a3a460047b47190d2964d73029bf33eb1)
Merge pull request #3 from TrinityCore/4.3.4

Merge 1/11/2014