feat: add config option to disable external link warning

Since it is heavily requested by users, this adds a new config option
to disable the previously introduced external link warning.
Be aware however, that disabling this config option weakens the
security of your HedgeDoc instance and is therefore only recommended
for closed trustworthy user groups.

Signed-off-by: Erik Michelson <github@erik.michelson.eu>

lib/config/default.js

@@ -193,5 +193,6 @@ module.exports = {
   //    3rd appearance: "31-good-morning-my-friend---do-you-have-5-2"
   linkifyHeaderStyle: 'keep-case',
   enableStatsApi: true,
+  externalLinkWarning: true,
   externalLinkWhitelist: []
 }

lib/config/environment.js

@@ -167,5 +167,6 @@ module.exports = {
   openID: toBooleanConfig(process.env.CMD_OPENID),
   linkifyHeaderStyle: process.env.CMD_LINKIFY_HEADER_STYLE,
   enableStatsApi: toBooleanConfig(process.env.CMD_ENABLE_STATS_API),
+  externalLinkWarning: toBooleanConfig(process.env.CMD_EXTERNAL_LINK_WARNING, true),
   externalLinkWhitelist: toArrayConfig(process.env.CMD_EXTERNAL_LINK_WHITELIST)
 }

lib/web/statusRouter.js

@@ -113,6 +113,7 @@ statusRouter.get('/config', function (req, res) {
     linkifyHeaderStyle: config.linkifyHeaderStyle,
     cookiePolicy: config.cookiePolicy,
     enableUploads: config.enableUploads,
+    externalLinkWarning: config.externalLinkWarning,
     externalLinkWhitelist: config.externalLinkWhitelist,
     userToken: req.user ? req.user.deleteToken : ''
   }