Add pre-commit

.git_hooks/install_hooks.sh

@@ -1,3 +0,0 @@
-#!/bin/sh
-
-ln -s ./../../.git_hooks/pre-commit .git/hooks/pre-commit

.git_hooks/pre-commit

@@ -1,3 +0,0 @@
-#!/bin/sh
-
-doctoc --title "# Table of Contents" .

.pre-commit-config.yaml

@@ -0,0 +1,15 @@
+repos:
+-   repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v2.3.0
+    hooks:
+    -   id: check-yaml
+    -   id: end-of-file-fixer
+    -   id: trailing-whitespace
+-   repo: https://github.com/psf/black
+    rev: 19.3b0
+    hooks:
+    -   id: black
+-   repo: https://github.com/thlorenz/doctoc
+    rev: v1.4.0
+    hooks:
+    -   id: doctoc