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

data_structures_and_algorithms/coins.py

@@ -1,57 +0,0 @@
-import unittest
-from math import floor
-
-################################################################################
-# Solution
-################################################################################
-
-# change_possibilities :: Int -> [Int] -> Int
-def change_possibilities(n, xs):
-    combinations = [0] * (n + 1)
-    combinations[0] = 1
-
-    for x in xs:
-        for i in range(len(combinations)):
-            if i >= x:
-                combinations[i] += combinations[i - x]
-
-    return combinations[n]
-
-
-################################################################################
-# Tests
-################################################################################
-class Test(unittest.TestCase):
-
-    def test_sample_input(self):
-        actual = change_possibilities(4, (1, 2, 3))
-        expected = 4
-        self.assertEqual(actual, expected)
-
-    def test_one_way_to_make_zero_cents(self):
-        actual = change_possibilities(0, (1, 2))
-        expected = 1
-        self.assertEqual(actual, expected)
-
-    def test_no_ways_if_no_coins(self):
-        actual = change_possibilities(1, ())
-        expected = 0
-        self.assertEqual(actual, expected)
-
-    def test_big_coin_value(self):
-        actual = change_possibilities(5, (25, 50))
-        expected = 0
-        self.assertEqual(actual, expected)
-
-    def test_big_target_amount(self):
-        actual = change_possibilities(50, (5, 10))
-        expected = 6
-        self.assertEqual(actual, expected)
-
-    def test_change_for_one_dollar(self):
-        actual = change_possibilities(100, (1, 5, 10, 25, 50))
-        expected = 292
-        self.assertEqual(actual, expected)
-
-
-unittest.main(verbosity=2)