Added support for macro arguments

tests/simple/macros.v

@@ -0,0 +1,9 @@
+module test(a, y);
+`define MSB_LSB_SEP :
+`define get_msb(off, len) ((off)+(len)-1)
+`define get_lsb(off, len) (off)
+`define sel_bits(offset, len) `get_msb(offset, len) `MSB_LSB_SEP `get_lsb(offset, len)
+input [31:0] a;
+output [7:0] y;
+assign y = a[`sel_bits(16, 8)];
+endmodule