[open] Change saved vars file

[Rhyono]

The indention in the saved vars is done by 4 spaces per level. Why not use tabs? I took a 1.5MB save file, converted every 4 spaces to 1 tab and the file size was literally halved.

I don't know how much those extra characters affect load/save times, but even if they don't: I know I wouldn't mind the extra HDD space.