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/graph-to-graphviz.py

@@ -0,0 +1,39 @@
+from graphviz import Digraph
+from collections import deque
+from fixtures import weighted_graph
+
+# There are three ways to model a graph:
+# 1. Edge list: [(Vertex, Vertex)]
+# 2. Neighbors table: Map(Vertex, [Vertex])
+# 3. Adjacency matrix: [[Boolean]]
+#
+# The following graph is a neighbors table.
+
+
+# to_graphviz :: Vertex -> Map(Vertex, [(Vertex, Weight)]) -> String
+def to_graphviz(start, g):
+    """Compiles the graph into GraphViz."""
+    d = Digraph()
+    q = deque()
+    seen = set()
+
+    q.append(start)
+
+    while q:
+        v = q.popleft()
+        if v in seen:
+            continue
+        d.node(v, label=v)
+
+        for w, x in g[v]:
+            d.edge(v, x, label=str(w))
+            q.append(x)
+        seen.add(v)
+
+    return d.source
+
+
+with open('/tmp/test.gv', 'w') as f:
+    src = to_graphviz('a', weighted_graph)
+    f.write(src)
+    print('/tmp/test.gv created!')