addon handler 1.0 (widget part)

changelog
 * addons := { widget, gadget }
 * new '/luaui callins' command !!!
 * auto linking of _all_ engine supported callins
 * new handler:AddNewCallIn() to add new custom callins at runtime
 * new require() to loads modules from "Lua*/Utilities/*.lua"
 * new addon rev2 format (much safer and bit faster)
 * new AddonLoaded callin
 * new AddonRemoved callin
 * new BlockAddon callin
 * handler now got a config.lua
 * addons can now be loaded from multiple dirs
 * step into unified handler between widgets & gadgets
 * widgetHandler: is now available via handler: too (unification)
 * new handler:SearchForNew()
 * safer removing of addons during callins