Core Import: Add Synthesis and PnR parameters

It would be useful to be able to control the parameters of synthesis and implementation directly from TaPaSCo. Maybe we should define modes, e.g.,

• fastest - lowest effort, minimal runtime
• fast - slightly slower, but still short runtime
• normal - default options
• optimal - slower, get as close to real values as possible
• aggressive_performance - maximal optimization to performance
• aggressive_area - maximal optimization area