Assigning the first set of pins
adding Pin Group classification to pins using the pinExplorer
assign then next sets of pins
build the PIN_GROUP_SYMBOL_MAP file
look at SmartFrac results with just the default pin_groups
look at smartfrac results with PIN_GROUPS and no PIN_GROUP_SYMBOL_MAP
SmartFrac results with PIN_GROUPS and PIN_GROUP_SYM_MAP_FILE