Shared/Build: Restore disabled warnings on Visual Studio

Restore 2 disabled warnings, 1 already disabled in CMake with the WITH_WARNINGS flag set to False and the other disabled by default as stated in VS documentation http://msdn.microsoft.com/en-us/library/aa984150.aspx
DB/Errors: Leftoever fixes

Work done by @untaught fixes #10747
DB/GameObject: Added gameobject "Dark Iron Mole Machine (Minion Summoner Trap)"
DB/SAI: The Battle of Valhalas Quest Chain

Fixes #8377
Consists of:
1) Battle at Valhalas: Fallen Heroes (13214)
2) Battle at Valhalas: Khit'rix the Dark Master (13215)
3) Battle at Valhalas: The Return of Sigrid Iceborn (13216)
4) Battle at Valhalas: Carnage! (13217)
5) Battle at Valhalas: Thane Deathblow (13218)
6) Battle at Valhalas: Final Challenge (13219)
Merge pull request #10827 from jackpoz/restore_warnings

Shared/Build: Restore disabled warnings on Visual Studio
Core/PathGenerator: Fix conditional jump on uninitialized value

Fix conditional jump on uninitialized value in PathGenerator::GetNavTerrain() by checking the result of getLiquidStatus() before accessing the LiquidData, uninitialized in case there's no water at all.

Valgrind log:
 Conditional jump or move depends on uninitialised value(s)
  at : PathGenerator::GetNavTerrain(float, float, float) (PathGenerator.cpp:553)
  by : PathGenerator::UpdateFilter() (PathGenerator.cpp:542)
  by : PathGenerator::CreateFilter() (PathGenerator.cpp:530)
  by : PathGenerator::PathGenerator(Unit const*) (PathGenerator.cpp:46)
  by : Spell::Spell(Unit*, SpellInfo const*, TriggerCastFlags, unsigned long, bool) (Spell.cpp:493)
  by : Unit::CastSpell(SpellCastTargets const&, SpellInfo const*, CustomSpellValues const*, TriggerCastFlags, Item*, AuraEffect const*, unsigned long) (Unit.cpp:846)
  by : Unit::CastSpell(Unit*, SpellInfo const*, TriggerCastFlags, Item*, AuraEffect const*, unsigned long) (Unit.cpp:882)
  by : Unit::CastSpell(Unit*, unsigned int, TriggerCastFlags, Item*, AuraEffect const*, unsigned long) (Unit.cpp:870)
  by : Unit::CastSpell(Unit*, unsigned int, bool, Item*, AuraEffect const*, unsigned long) (Unit.cpp:858)
  by : Player::SendInitialPacketsAfterAddToMap() (Player.cpp:22580)
  by : WorldSession::HandleMoveWorldportAckOpcode() (MovementHandler.cpp:121)
  by : WorldSession::HandleMoveWorldportAckOpcode(WorldPacket&) (MovementHandler.cpp:37)
Core/SAI: Make SMART_ACTION_RANDOM_MOVE also work with SMART_TARGET_NONE and non-creature targets (if a non-creature target_type is specified and no creature target was found, the action is fired at the source)

Ref. #7431
Merge branch 'upstream/master'