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/crack_the_coding_interview/to_tree.hs

@@ -0,0 +1,11 @@
+data Tree a = Node a [Tree a] deriving (Show)
+
+withRoot :: [a] -> [Tree a]
+withRoot xs = xs |> toThing |> fmap buildTree
+
+buildTree :: (a, [a])
+
+
+toTree :: [a] -> Tree a
+toTree [x]      = Node x []
+toTree [x | xs] = Node x (toTree xs)