interface and instance array support

- support for interface instance arrays
- support for interface-using module instance arrays
- support for modport array bindings
- fix modport bindings shadowed in nested instances

test/basic/interface_array_single.sv

@@ -0,0 +1,49 @@
+`define SHADOW \
+    integer i; \
+    Interface intfs[1:0]();
+
+interface Interface;
+    integer x;
+    modport ModportA(input .x(x + 1));
+    modport ModportB(input .x(x + 2));
+endinterface
+
+module ModuleA(intf);
+    Interface intf;
+    `SHADOW
+    initial #1 $display("ModuleA got %0d", intf.x);
+    ModuleN n(intf);
+endmodule
+
+module ModuleB(intf);
+    Interface.ModportA intf;
+    `SHADOW
+    initial #1 $display("ModuleB got %0d", intf.x);
+    ModuleN n(intf);
+endmodule
+
+module ModuleC(intf);
+    Interface.ModportB intf;
+    `SHADOW
+    initial #1 $display("ModuleC got %0d", intf.x);
+    ModuleN n(intf);
+endmodule
+
+module ModuleN(intf);
+    Interface intf;
+    `SHADOW
+    initial #1 $display("ModuleN got %0d", intf.x);
+endmodule
+
+module top;
+    Interface intfs[4:8]();
+    `define LOOP for (genvar i = 4; i <= 8; ++i)
+    `LOOP initial intfs[i].x = i ** 2;
+    `LOOP ModuleA a1(intfs[i]);
+    `LOOP ModuleA a2(intfs[i].ModportA);
+    `LOOP ModuleA a3(intfs[i].ModportB);
+    `LOOP ModuleB b1(intfs[i]);
+    `LOOP ModuleB b2(intfs[i].ModportA);
+    `LOOP ModuleC c1(intfs[i]);
+    `LOOP ModuleC c2(intfs[i].ModportB);
+endmodule