Changes to allow decoder height to be a 2x multiple of bitcell height.
Split of control logic tests.
Fixed track spacing in SRAM and channel router
PEP8 cleanup.
this is the first step to allow engineers, porting technologies, more room
for routing their handmade cells.
For now, we don't allow the specification of power_grids where the lower layer
prefers to be routed vertically. This is due to the router not
connecting some pins properly in that case.
Signed-off-by: Bastian Koppelmann <kbastian@mail.uni-paderborn.de>