[2871] Implement Onyxia Kite-Prevention ability.

Thanks to alexluana for researching the use of this spell

Note to DBDevs: Spells started with 21131 need information in spell_target_position table
[2872] Implement Onyxia spell Heated Ground

Note: Adapt your mangosd.conf to have a larger value for "MaxSpellCastsInChain" (12 is required, better be safe than sorry and use a big value :-) )