Tidy up structure of briefcase

I had a spare fifteen minutes and decided that I should tidy up my
monorepo. The work of tidying up is not finished; this is a small step in the
right direction.

TL;DR
- Created a tools directory
- Created a scratch directory (see README.md for more information)
- Added README.md to third_party
- Renamed delete_dotfile_symlinks -> symlinkManager
- Packaged symlinkManager as an executable symlink-mgr using buildGo

scratch/data_structures_and_algorithms/conways-game-of-life.py

@@ -0,0 +1,78 @@
+from itertools import product
+from random import choice
+from time import sleep
+from os import system
+from math import floor
+from colorama import Back, Fore, Style
+
+################################################################################
+# Simulation of Conway's Game of Life. The goal here was to write this with a
+# small amount of code as a proof-of-concept that could be run in the terminal.
+#
+# If you'd like to tinker with the rules, see the conditionals defined in the
+# `advance/1` function. For other parameters, like the board size and refresh
+# rate, refer to the while-loop defined at the bottom of this file.
+################################################################################
+
+
+def init_board(n, init_alive_percentage):
+    """Initialize a board of size `n` by `n`. Supply a percentage,
+    `init_alive_percentage`, representing the number of cells in the board that
+    should be alive from the start."""
+    alive_count = floor(n * init_alive_percentage)
+    distribution = [True] * alive_count + [False] * (n - alive_count)
+    return [[choice(distribution) for _ in range(n)] for _ in range(n)]
+
+
+def neighbors(coord, board):
+    """Return the neighbors for a given `coord` on a `board`."""
+    n = len(board)
+    row, col = coord
+    return [
+        board[(row + row_d) % n][(col + col_d) % n]
+        for row_d, col_d in product([-1, 0, 1], [-1, 0, 1])
+        if (row_d, col_d) != (0, 0)
+    ]
+
+
+def advance(board):
+    """Advance the state of the `board` from T[n] to T[n+1]."""
+    n = len(board)
+    new_board = [[False for _ in range(n)] for _ in range(n)]
+    for row in range(n):
+        for col in range(n):
+            alive_count = len([x for x in neighbors((row, col), board) if x])
+            # Loneliness
+            if alive_count == 0:
+                new_board[row][col] = False
+            # Status Quo
+            elif alive_count == 1:
+                new_board[row][col] = board[row][col]
+            # Cooperation
+            elif alive_count == 2:
+                new_board[row][col] = True
+            # Resource starvation
+            elif alive_count >= 3:
+                new_board[row][col] = False
+    return new_board
+
+
+def print_board(board):
+    """Print the game `board` in a human-readable way."""
+    result = ''
+    for row in board:
+        for col in row:
+            if col:
+                result += Back.GREEN + '1 ' + Style.RESET_ALL
+            else:
+                result += Back.RED + '0 ' + Style.RESET_ALL
+        result += '\n'
+    print(result)
+
+
+board = init_board(100, 0.50)
+while True:
+    system('clear')
+    print_board(board)
+    sleep(0.15)
+    board = advance(board)