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_slice_tb.v

@@ -0,0 +1,53 @@
+module Test();
+    parameter BASE = 0;
+    parameter SIZE = 0;
+    parameter DIR = 0;
+
+    localparam LEFT = BASE;
+    localparam RIGHT = BASE + DIR * (SIZE - 1);
+
+    genvar left, right, offset;
+    generate
+        for (left = LEFT + SIZE; left <= RIGHT + SIZE; left = left + 1)
+        for (right = LEFT + SIZE; right <= RIGHT + SIZE; right = right + 1)
+        if ((left - right) * DIR <= 0)
+        for (offset = -2 + SIZE; offset <= 2 + SIZE; offset = offset + 1)
+        begin
+
+        Instance #(
+            LEFT, RIGHT,
+            left - SIZE, right - SIZE, offset - SIZE
+        ) i();
+
+        initial begin
+            i.xs = 1;
+            while (i.xs != 0) begin
+                #1;
+                $display("LEFT=%2d RIGHT=%2d INNER_LEFT=%2d INNER_RIGHT=%2d INNER_OFFSET=%2d i.xs=%b i.l.xs=%b i.m.xs=%b i.n.xs=%b",
+                    LEFT, RIGHT,
+                    left - SIZE, right - SIZE, offset - SIZE,
+                    i.xs, i.l.xs, i.m.xs, i.n.xs);
+                i.xs = i.xs + 1;
+            end
+        end
+
+        end
+    endgenerate
+endmodule
+
+module Suite();
+    parameter SIZE = 0;
+    genvar base;
+    generate
+        for (base = -2 + SIZE; base <= 2 + SIZE; base = base + 1) begin
+            Test #(base - SIZE, SIZE, -1) b();
+            Test #(base - SIZE, SIZE, 1) f();
+        end
+    endgenerate
+endmodule
+
+module top;
+    Suite #(2) s2();
+    Suite #(3) s3();
+    Suite #(4) s4();
+endmodule