Started work on Lua modding system.

Well... if something will work then I'll describe it.
Stared work on nodes.

Add ISerializable interface.
Add INode interface.
Add Node class (Node parameters handling)

Update N/A.

Fix N/A.
Changed Node handling.

Setters are moved to private section. There is one method create() to
setup whole Node data. It is not needed to allow user to modify Node
parameters by public setters in case that Node is defined in Lua
scripts.

File system and Lua update with methods to get game and user
directories.

Add N/A.

Update FileSystem service.
Update Lua service.
Update Node implementation.

Fix N/A.