Blender Git Loki

Bugfix #5959

Save .blend file: when setting option "Relative Paths", blender tried to
save in the root directory.
Saving .blend files is always with a real path, do the relative option
should be skipped.

Also removed the totally annoying error popup when trying to save something
before you saved a .blend. That warning was almost never correct. I left
in this warning for loading files btw.