Core/PacketIO: Corrected structures of SMSG_PARTY_MEMBER_STATS and SMSG_PARTY_MEMBER_STATS_FULL, fixes weird pet behavior in groups (appearing as "Unknown", breaking combat logs)

Closes #345
Core/Spells: Fixed a silly typo in SpellInfo::_IsPositiveEffect.

Fixes some auras being displayed as debuffs while they should not. (Just see Invisibility #66)

Ref. #7912
Core/Spells: Fix a logging message error
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Added Cross-Faction Battlegrounds.
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This reverts commit e59f5d7376ef3c3a1057404afdb26d45c2e2c29e.
Revert "Added."

This reverts commit 5dcf05153d41a85c1d3c2ab1151972d85763b728.
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Drop Useless SQL(s).
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Update.
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