Advanced Lua scripts configuration in omwaddon

Support in omwaddon:

• Attaching Lua scripts to specific records.
• Attaching Lua scripts to specific references.
• Ability to add custom Lua data to any record or reference.
• Custom Lua data in omwaddon can contain links to other references including references in other content files.
• Lua scripts (and custom data) can be attached to records/references from other content files without overriding the records/references. It means that several mods can work with one objects without conflicts. Also it means that a mod can contain a big .esp (compatible with morrowind.exe) and a small .omwaddon that adds Lua scripts to the objects in the main .esp.

openmw-cs can not create such omwaddons yet.

I would like to merge this MR before 0.48 (so 0.48 will be able to load future omwaddons) and postpone the work on openmw-cs to 0.49.