N°5621 Move showdown 2.0.0-alpha1 to NPM

Current file header is : /*! showdown v 2.0.0-alpha1 - 25-09-2018 */

Official 2.0.0-alpha doesn't match neither on content nor date :(
Considering date we would be at 1.8.7, but it is also quite different (and has vulnerabilities)
In consequence switching to 2.0.0.

node_modules/ansi-regex/package.json

@@ -0,0 +1,55 @@
+{
+	"name": "ansi-regex",
+	"version": "5.0.1",
+	"description": "Regular expression for matching ANSI escape codes",
+	"license": "MIT",
+	"repository": "chalk/ansi-regex",
+	"author": {
+		"name": "Sindre Sorhus",
+		"email": "sindresorhus@gmail.com",
+		"url": "sindresorhus.com"
+	},
+	"engines": {
+		"node": ">=8"
+	},
+	"scripts": {
+		"test": "xo && ava && tsd",
+		"view-supported": "node fixtures/view-codes.js"
+	},
+	"files": [
+		"index.js",
+		"index.d.ts"
+	],
+	"keywords": [
+		"ansi",
+		"styles",
+		"color",
+		"colour",
+		"colors",
+		"terminal",
+		"console",
+		"cli",
+		"string",
+		"tty",
+		"escape",
+		"formatting",
+		"rgb",
+		"256",
+		"shell",
+		"xterm",
+		"command-line",
+		"text",
+		"regex",
+		"regexp",
+		"re",
+		"match",
+		"test",
+		"find",
+		"pattern"
+	],
+	"devDependencies": {
+		"ava": "^2.4.0",
+		"tsd": "^0.9.0",
+		"xo": "^0.25.3"
+	}
+}