Fix crash with /reload npcs
Merge pull request #73 from dalkon/master

Fix crash with /reload npcs
Code cleanup

This commit also assures that Npc::closeAllShopWindows won't get stuck
in an infinite loop.
New Lua functions

Player & Creature constructors now accept a string (name) as an
argument.
Creature:registerEvent & Creature:unregisterEvent has been added.
Moved registerCreatureEvent to compat.lua
Merge pull request #75 from dalkon/master

Some Lua stuff