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/deepmind/dijkstra.py

@@ -1,26 +0,0 @@
-# Doing a practice implementation of Dijkstra's algorithm: a priority-first
-# search.
-from heapq import heappush, heappop
-
-
-class Node(object):
-    def __init__(self, value, children):
-        self.value = value
-        self.children = children
-
-
-def shortest_path(a, b):
-    """Return the shortest path from `a` to `b`."""
-    q = []
-    seen = set()
-    heappush((a.value, a, [a]), q)
-
-    while q:
-        d, node, path = heappop(q)
-        if node == b:
-            return path
-        seen.add(node)
-        for child in node.children:
-            if child not in seen:
-                heappush((d + child.value, child, path + [child]), q)
-    raise Exception("Path between nodes A and B does not exist.")