Monster events & Lua changes

You can now properly compare userdata, for example (player == player)
correctly.
New Lua functions
creature:canSee()
creature:canSeeCreature()
creature:setTarget()
creature:getFollowCreature()
creature:setFollowCreature()
creature:setMaster()
monster:isOpponent()
monster:isFriend()
monster:selectTarget()
New creatureevents & Lua functions

onChangeHealth
onChangeMana

monster:isIdle()
monster:setIdle()
MonsterType class for Lua

Game.getSpectators & Game.getPlayers was also added.
More Lua functions
Bugfix for text messages.
Merge pull request #177 from dalkon/master

Monster events & Lua changes