global refactor to use items class code

[ThomasWaldmann]

see PR #981.

[enkore]

With #1037 looking very good now (just have to test it practically), I think we can merge the windows branch back into master before doing the large refactors we have planned. It would certainly make it much easier :)

[ThomasWaldmann]

I'ld prefer if the windows stuff stays seperate for quite a while.