Core/Misc: Fix some static analysis issues

Fix some static analysis issues about missing NULL checks.
Pass safe Creature pointer instead of summoning a Creature, passing the GUID and retrieve the same Creature from GUID.
Core/Chat: Fix ChatFlood.MessageCount not being handled correctly

Fix Anti-flood chat system to always allow 1 more message than the count specified in the ChatFlood.MessageCount config parameter.
Core/SmartAI: Fix SMART_ACTION_ALLOW_COMBAT_MOVEMENT
Core/SmartScript: Allow flag to be added to spell to determine combat movement.
Greatly simplifies SAI combat scripting.
Scripting/Sholazar Basin: Fix warning
Core/SmartAI: Fixed waypoint pathing not resuming after evade.
DB/SAI: Replace a couple bad scripts...not mine :)
Core/SmartAI: Remove unneeded code added in error
Scripting/Blade's Edge: Quest 10594 "Gauging the Resonant Frequency"
Closes #6214
Core/SpellMgr: Remove unneeded check for max targets
Core/Commands: Fix NULL dereference crash in .npc set link

Fix NULL dereference crash in .npc set link happening when passing a not-existent Creature guid as parameter, es. ".npc set link -1" .
Issue spotted by static analysis, added in c05ed659cbc561b6e7c0016cc7b1548886d5337a
DB/SAI: Fix SAI for Terrorspark Closes #9999
Core/RBAC: Fix typo
Scripts/Oculus: fix drake spells

Closes #6681
Closes #6680
Closes #6673
DB/SAI: Fix SAI script for Denalan. Closes #6758