Replace draw_divider setting with draw_(soft|hard)_divider

Previous variant was bad because
1. draw_divider only applied to soft dividers. Hard dividers were always drawn
2. But there was a hack with width=auto segments: for this segments draw_divider 
   setting applied always.

Now there are no additional dependencies: draw_*_divider applies no matter what 
other properties of the segment are.
Remove not present kwargs
Replace draw_soft_divider setting with draw_inner_divider

If weather or system_load segments were moved to the left draw_soft_divider 
variant resulted in incorrect renderring. Thus it was replaced by 
draw_inner_divider.