Make synthesis and implementation effort configurable
The default settings used at the moment are AlternateRoutability + Retiming for Synthesis and Explore + PHYS_OPT_DESIGN for Implementation. These settings could be considered to be very high effort. A switch could be added to let the user decide between different "effort levels". For most synthesis runs it is not necessary to go with very high effort and the user might be happy about the much lower run-time.