Speed Hack Control #342
user kills, Meat Dumpling gifts.
logic bug fixed.
Merge pull request #373 from Eridia/master

Game server: hardcoded speed hack checks, Meat dumpling rewards.
Game server: fixed an invalid AG_USER_REGENE packet sent by resurrection skills.
Game server: fixed blinking when resurrected. It should also now blink correctly (and update the AI server properly) when you aren't resurrected.
Game server: removed the unofficial speedhack notice & ensured the movement packet handler is no longer handled on speedhack detection.
Game server: removed CUser::ChangeNP() (redundant method, need to clean up LoyaltyChange() & LoyaltyDivide() first).
Game server: fixed a bug with the killer's var being overwritten when giving Meat Dumplings to a party (so subsequent rewards would use the last party member, or nullptr!). Defined the Meat Dumpling item & implemented a standard range for party rewards to apply.
Game server: fixed a problem with speed hack detection; the speed is meant to be signed, with the speed unsigned it wraps negative (i.e. moving backwards) speeds around, which makes it think it's speed hacking.
Various NPC attack logic fixes (this is *really* messy).
Fixes death animation being sent twice on some occasions (not noticeable by the client anyway).
Fixes multiple OnDeath() handling.
Fixes NPCs losing double the damage (removed the manual HP update), making the HP bar reading inconsistent with the actual data; resolves #368.
Fixes NPC attacks on users not triggering the OnDeath() handler in rare circumstances; refs #357.
Fixes users being seen as alive after respawning when blinking's disabled.
Game server: PVP zone respawns now use coordinates from the START_POSITION table, as per official; resolves #376.
Replaced a magic number zone IDs.
Game server/skill system: fixed a bug with curse reflection failing when reflected onto the caster (self-cast check was added later); resolves #362.
Game server/quest system: removed global function bindings for original scripts when building for our unofficial scripts.
Game server/quest system: CastSkill() now returns a boolean indicating whether the skill was successful or not.
Game server/skill system: skill prerequisites are now checked in IsAvailable() (i.e. before taking any items) instead of before the skill's executed.
Game server/skill system: buffs already cast on the target now cause the skill to fail before taking mana/items, etc; refs #261.
Game server/skill system: stops "cat's eyes" from applying to the party.
Game server: fixed letter items being placed in the wrong slot; resolves #380.