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.

third_party/lisp/linear-programming.nix

@@ -0,0 +1,26 @@
+{ depot ? import <depot> {}, ... }:
+
+let
+  src = builtins.fetchGit {
+    url = "https://github.com/neil-lindquist/linear-programming.git";
+    rev = "8c8d55e7584773b90c4ba4b225c5f2008f4c474a";
+  };
+in depot.nix.buildLisp.library {
+  name = "linear-programming";
+  deps = [
+    (depot.nix.buildLisp.bundled "uiop")
+    depot.third_party.lisp.iterate
+    depot.third_party.lisp.alexandria
+  ];
+  srcs = [
+    "${src}/src/conditions.lisp"
+    "${src}/src/expressions.lisp"
+    "${src}/src/simplex.lisp"
+    "${src}/src/system-info.lisp"
+    "${src}/src/utils.lisp"
+    "${src}/src/problem.lisp"
+    "${src}/src/solver.lisp"
+    "${src}/src/external-formats.lisp"
+    "${src}/src/all.lisp"
+  ];
+}