New command line LedgerTool. (RIPD-243)

* Retrieve and process summary or full ledgers.
* Search using arbitrary criteria (any Python function).
* Search using arbitrary formats (any Python function).
* Caches ledgers as .gz files to avoid repeated server requests.
* Handles ledger numbers, ranges, and special names like validated or closed.

bin/ripple/util/test_Function.py

@@ -0,0 +1,25 @@
+from __future__ import absolute_import, division, print_function, unicode_literals
+
+from ripple.util.Function import Function, MATCHER
+
+from unittest import TestCase
+
+def FN(*args, **kwds):
+    return args, kwds
+
+class test_Function(TestCase):
+    def match_test(self, item, *results):
+        self.assertEquals(MATCHER.match(item).groups(), results)
+
+    def test_simple(self):
+        self.match_test('function', 'function', '')
+        self.match_test('f(x)', 'f', '(x)')
+
+    def test_empty_function(self):
+        self.assertEquals(Function()(), None)
+
+    def test_function(self):
+        f = Function('ripple.util.test_Function.FN(True, {1: 2}, None)')
+        self.assertEquals(f(), ((True, {1: 2}, None), {}))
+        self.assertEquals(f('hello', foo='bar'),
+                          (('hello', True, {1: 2}, None), {'foo':'bar'}))