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/advent-of-code/day_1.py

@@ -1,119 +0,0 @@
-from math import floor
-
-xs = [
-    102473,
-    84495,
-    98490,
-    68860,
-    62204,
-    72810,
-    65185,
-    145951,
-    77892,
-    108861,
-    70764,
-    67286,
-    74002,
-    80773,
-    52442,
-    131505,
-    107162,
-    126993,
-    59784,
-    64231,
-    91564,
-    68585,
-    98735,
-    69020,
-    77332,
-    60445,
-    65826,
-    111506,
-    95431,
-    146687,
-    135119,
-    86804,
-    95915,
-    85434,
-    111303,
-    148127,
-    132921,
-    136213,
-    89004,
-    143137,
-    144853,
-    143017,
-    104386,
-    100612,
-    54760,
-    63813,
-    144191,
-    84481,
-    69718,
-    84936,
-    98621,
-    124993,
-    92736,
-    60369,
-    137284,
-    101902,
-    112726,
-    51784,
-    126496,
-    85005,
-    101661,
-    137278,
-    136637,
-    90340,
-    100209,
-    53683,
-    50222,
-    132060,
-    98797,
-    139054,
-    135638,
-    100632,
-    137849,
-    125333,
-    103981,
-    76954,
-    134352,
-    74229,
-    93402,
-    62552,
-    50286,
-    57066,
-    98439,
-    120708,
-    117827,
-    107884,
-    72837,
-    148663,
-    125645,
-    61460,
-    120555,
-    142473,
-    106668,
-    58612,
-    58576,
-    143366,
-    90058,
-    121087,
-    89546,
-    126161,
-]
-
-
-def fuel_for_mass(x):
-    """Return the amount of fuel (in mass) required for a mass of X. The total
-    amount of fuel includes the amount of fuel required for the fuel itself,
-    since fuel also has a mass weights."""
-    mass_fuel = floor(x / 3) - 2
-    if mass_fuel < 0:
-        return 0
-    else:
-        fuel_fuel = fuel_for_mass(mass_fuel)
-        return mass_fuel + fuel_fuel
-
-
-print(sum(fuel_for_mass(x) for x in xs))