Blender Git Loki

Fix T41704: 2.71.6 no longer reading user ui panel arrangement from earlier saved blend files.

This reverts rB52c06440d8e51c8661a679bcb33742666ce8dbf9 and rBe40d8258bb46926a1aecf51236822532397993f3
(tabname is old 2.4x tabed panels system, *not* new 2.7x tool tabs!).

Also disabled (#idef'ed) everything regarding tabname/tabed panels for now, we may even remove it completely,
would make things clearer imho.

Note files saved with 2.71.6 up till now would have two versions of some panels in store (with two different
values for their tabname), can give some order oddities in those cases, which have to be fixed by hand...