[12535] Loot-System: Fix reference loading check

This fixes a false error output for loot references that are only used with spell loot.

Thanks to X-Savior for properly reporting both error messages and use case
[12536] Fix use of config values related to quest-status and level

This fixes use of negative value in config values Quests.LowLevelHideDiff and Quests.HighLevelHideDiff

Also add some documentation around the related code

Thanks to Neotmiren for pointing and to cala for testing.
[12537] Immediately remove corpses when ForcedDespawn is used

Thanks to Neotmiren for pointing, special thanks to cala for testing!

Close cmangos/issues#222
[mr2862] define two transport-related DBC structures
[mr2863] set new default to max cast counter (255). one uint32 value economy. related to #1378
[mr2864] add some compartibility wrappers (unification), no real changes.
SD2 update
[mr2865] correct type definition
[12538] Implement some custom use for Effect Activate Object spells

This will fix the summoning events for the Wind Stones, Ice Stones, Skettis bosses and quest 11865

Close scriptdev2/scriptdev2#50
[12539] Update some Sunwell Plateau spells

Limit targets and allow positive effect for spell 46650
Implement effect for spells 46289 and 46637
Remove effect for spell 44845 - will be handled in script library
SD2 update
[mr2866] fix RaiseDead with creature corpse. also some additional checks for special target source method. related to #1383
Merge https://github.com/mangosR2/mangos into SPP