add examples and integrate into build

I suppose the next step will be to translate the C examples into their
zig counterparts. This is also good dog food.

examples/request_reply.zig

@@ -0,0 +1,41 @@
+const std = @import("std");
+const nats = @import("nats");
+
+fn onMessage(
+    userdata: *bool,
+    connection: *nats.Connection,
+    subscription: *nats.Subscription,
+    message: *nats.Message,
+) void {
+    _ = subscription;
+
+    std.debug.print("Subject \"{s}\" received message: \"{s}\"\n", .{
+        message.getSubject(),
+        message.getData() orelse "[null]",
+    });
+
+    if (message.getReply()) |reply| {
+        connection.publishString(reply, "salutations") catch @panic("HELP");
+    }
+
+    userdata.* = true;
+}
+
+pub fn main() !void {
+    const connection = try nats.Connection.connectTo(nats.default_server_url);
+    defer connection.destroy();
+
+    var done = false;
+    const subscription = try connection.subscribe(bool, "channel", onMessage, &done);
+    defer subscription.destroy();
+
+    while (!done) {
+        const reply = try connection.requestString("channel", "greetings", 1000);
+        defer reply.destroy();
+
+        std.debug.print("Reply \"{s}\" got message: {s}\n", .{
+            reply.getSubject(),
+            reply.getData() orelse "[null]",
+        });
+    }
+}