flowmap: clean up terminology.
flowmap: clean up terminology.

  * "map": group gates into LUTs;
  * "pack": replace gates with LUTs.

This is important because we have FlowMap and DF-Map, and currently
our messages are ambiguous.

Also clean up some other log messages while we're at it.

SymbiFlow/yosys,SymbiFlow/yosys,YosysHQ/yosys,YosysHQ/yosys,cliffordwolf/yosys,cliffordwolf/yosys,YosysHQ/yosys,SymbiFlow/yosys,cliffordwolf/yosys,antmicro/yosys,cliffordwolf/yosys,antmicro/yosys,antmicro/yosys,antmicro/yosys,SymbiFlow/yosys,YosysHQ/yosys,YosysHQ/yosys,SymbiFlow/yosys,YosysHQ/yosys,antmicro/yosys,YosysHQ/yosys,cliffordwolf/yosys,antmicro/yosys,SymbiFlow/yosys,cliffordwolf/yosys,SymbiFlow/yosys,cliffordwolf/yosys,SymbiFlow/yosys,YosysHQ/yosys,antmicro/yosys,cliffordwolf/yosys,antmicro/yosys,cliffordwolf/yosys