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.

data_structures_and_algorithms/bit-manipulation.py

@@ -0,0 +1,32 @@
+def test(x, i):
+    return x & (1 << i) != 0
+
+
+def set(x, i):
+    return x | (1 << i)
+
+
+def clear(x, i):
+    return x & ~(1 << i)
+
+
+def toggle(x, i):
+    if test(x, i):
+        return clear(x, i)
+    else:
+        return set(x, i)
+
+
+def test_single(x):
+    if x == 0:
+        return False
+    else:
+        return x & (x - 1) == 0
+
+
+print(test(0b1010, 3))
+print('{0:b}'.format(set(0b1010, 1)))
+print('{0:b}'.format(clear(0b1010, 1)))
+print('{0:b}'.format(toggle(0b1010, 2)))
+print(test_single(0b1010))
+print(test_single(0b1000))