Splice ./universe directory into ./

Manually merging:
- README.md: I added the description from universe/README.md into the heading of
  dotfiles/README.md.
- .envrc: dotfiles/.envrc was a superset of universe/.envrc
- .gitignore: Adding some of the ignored patterns from universe/.gitignore to
  dotfiles/.gitignore

Everything else here should be a simple rename.

universe/data_structures_and_algorithms/queue-two-stacks.py

@@ -1,66 +0,0 @@
-import unittest
-
-
-################################################################################
-# Solution
-################################################################################
-class QueueTwoStacks(object):
-    def __init__(self):
-        self.a = []
-        self.b = []
-
-    def enqueue(self, x):
-        self.a.append(x)
-
-    def dequeue(self):
-        if self.b:
-            return self.b.pop()
-        else:
-            while self.a:
-                self.b.append(self.a.pop())
-            return self.dequeue()
-
-
-################################################################################
-# Tests
-################################################################################
-class Test(unittest.TestCase):
-    def test_basic_queue_operations(self):
-        queue = QueueTwoStacks()
-        queue.enqueue(1)
-        queue.enqueue(2)
-        queue.enqueue(3)
-        actual = queue.dequeue()
-        expected = 1
-        self.assertEqual(actual, expected)
-        actual = queue.dequeue()
-        expected = 2
-        self.assertEqual(actual, expected)
-        queue.enqueue(4)
-        actual = queue.dequeue()
-        expected = 3
-        self.assertEqual(actual, expected)
-        actual = queue.dequeue()
-        expected = 4
-        self.assertEqual(actual, expected)
-
-    def test_error_when_dequeue_from_new_queue(self):
-        queue = QueueTwoStacks()
-        with self.assertRaises(Exception):
-            queue.dequeue()
-
-    def test_error_when_dequeue_from_empty_queue(self):
-        queue = QueueTwoStacks()
-        queue.enqueue(1)
-        queue.enqueue(2)
-        actual = queue.dequeue()
-        expected = 1
-        self.assertEqual(actual, expected)
-        actual = queue.dequeue()
-        expected = 2
-        self.assertEqual(actual, expected)
-        with self.assertRaises(Exception):
-            queue.dequeue()
-
-
-unittest.main(verbosity=2)