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/bracket-validator.py

@@ -1,63 +0,0 @@
-import unittest
-
-
-################################################################################
-# Solution
-################################################################################
-# is_valid :: String -> Boolean
-def is_valid(xs):
-    s = []
-    seeking = {
-        '}': '{',
-        ']': '[',
-        ')': '(',
-    }
-    openers = seeking.values()
-    closers = seeking.keys()
-    for c in xs:
-        if c in openers:
-            s.append(c)
-        elif c in closers:
-            if not s:
-                return False
-            elif s[-1] != seeking.get(c):
-                return False
-            else:
-                s.pop()
-    return len(s) == 0
-
-
-################################################################################
-# Tests
-################################################################################
-class Test(unittest.TestCase):
-    def test_valid_short_code(self):
-        result = is_valid('()')
-        self.assertTrue(result)
-
-    def test_valid_longer_code(self):
-        result = is_valid('([]{[]})[]{{}()}')
-        self.assertTrue(result)
-
-    def test_interleaved_openers_and_closers(self):
-        result = is_valid('([)]')
-        self.assertFalse(result)
-
-    def test_mismatched_opener_and_closer(self):
-        result = is_valid('([][]}')
-        self.assertFalse(result)
-
-    def test_missing_closer(self):
-        result = is_valid('[[]()')
-        self.assertFalse(result)
-
-    def test_extra_closer(self):
-        result = is_valid('[[]]())')
-        self.assertFalse(result)
-
-    def test_empty_string(self):
-        result = is_valid('')
-        self.assertTrue(result)
-
-
-unittest.main(verbosity=2)