Abstraction: a central getenv() feature to wrap all the system-specific things
Netlist compare debug and options can be enabled through environment variables:
KLAYOUT_NETLIST_COMPARE_DEBUG_NETCOMPARE=1: print netlist compare debug info
KLAYOUT_NETLIST_COMPARE_DEBUG_NETGRAPH=1: print net grapg
KLAYOUT_NETLIST_COMPARE_CASE_SENSITIVE=1: make netlist compare case sensitive