Add mailbox command
Renamed method
Merge pull request #11299 from Carbenium/MailboxCmd

Core/Command: Add mailbox command
Core/Misc: Fix crash
Core/Creature: Fix compile and logic in previous pull request. Also implemented UNIT_NPC_FLAG_MAILBOX.

Thanks @Shauren
Merge pull request #11469 from Dehravor/timetest-crash

Core/Misc: Fix crash
Misc/SQL: Rename SQL from fa2616fe4efa4651d48710c7458cd2d479e9338b
CoreCore/CrashHandler: Handle CRT asserts in Windows build

Handle CRT asserts in Windows crash handler instead of popping up a Abort/Retry/Ignore window