Core/SAI: Fix text over errors
Core/LFG: Fix Leader flag being ignored

Fix bug added in 5ca00bc14d38c5ad49f0ab4500af52e645133826 that removed Leader flag of LFG without ever adding it back, giving leadership to players who didn't want it.
Core/SAI: Ingore text valid errors for SMART_TARGET_CREATURE_DISTANCE / SMART_TARGET_CREATURE_RANGE / SMART_TARGET_CLOSEST_CREATURE
Merge branch 'master' of https://github.com/TrinityCore/TrinityCore into ghbb