Add ECM support, improve stream handling, and add the committed_padder component. The RGMII driver now handles the AXI4-Stream interface, with various stream tools added and updated.

lib/nsl_amba/axi4_stream/Makefile

@@ -4,6 +4,7 @@ vhdl-sources += axi4_stream_width_adapter.vhd
 vhdl-sources += axi4_stream_header_extractor.vhd
 vhdl-sources += axi4_stream_header_inserter.vhd
 vhdl-sources += axi4_stream_protocol_assertions.vhd
+vhdl-sources += axi4_stream_prefill_buffer.vhd
 
 deps += nsl_math.arith
 deps += nsl_logic.bool