UT: Lots of improvements and fixes.

- Parse negative amounts.
- Make Amount.negate() return a new value.
- Add Amount.equals().
- Rename Remote.trace() to set_trace().
- Fix request_ripple_balnce.
- Add more tests to send-test.js.
- Add more tests to amount-test.js.
- Add helper functions create_accounts and credit_limits to
  testutils.js.

test/testutils.js

@@ -1,3 +1,6 @@
+var async   = require("async");
+// var buster  = require("buster");
+
 var Remote  = require("../js/remote.js").Remote;
 var Server  = require("./server.js").Server;
 
@@ -28,6 +31,49 @@ var test_teardown = function (done, host) {
     .connect(false);
 };
 
+var create_accounts = function (remote, src, amount, accounts, callback) {
+  assert(5 === arguments.length);
+
+  async.forEachSeries(accounts, function (account, callback) {
+    remote.transaction()
+      .payment(src, account, amount)
+      .set_flags('CreateAccount')
+      .on('proposed', function (m) {
+	  // console.log("proposed: %s", JSON.stringify(m));
+
+	  callback(m.result != 'tesSUCCESS');
+	})
+      .on('error', function (m) {
+	  // console.log("error: %s", JSON.stringify(m));
+
+	  callback(m);
+	})
+      .submit();
+    }, callback);
+};
+
+var credit_limit = function (remote, src, amount, callback) {
+  assert(4 === arguments.length);
+
+  remote.transaction()
+    .ripple_line_set(src, amount)
+    .on('proposed', function (m) {
+	// console.log("proposed: %s", JSON.stringify(m));
+
+	// buster.assert.equals(m.result, 'tesSUCCESS');
+
+	callback(m.result != 'tesSUCCESS');
+      })
+    .on('error', function (m) {
+	// console.log("error: %s", JSON.stringify(m));
+
+	callback(m);
+      })
+    .submit();
+};
+
+exports.create_accounts = create_accounts;
+exports.credit_limit = credit_limit;
 exports.test_setup = test_setup;
 exports.test_teardown = test_teardown;