Fix language choice for server-side generation

srv.js

@@ -14,7 +14,7 @@ app.set('view engine', 'pug');
 app.use(express.static('./static'));
 
 app.use(function(req, res, next) {
-  let locale = req.query.lang || req.headers['accept-language'] || '';
+  let locale = req.query.changeLang || req.query.lang || req.headers['accept-language'] || '';
   req.i18n = new i18n();
   if (locale.indexOf('en') !== -1
       && locale.indexOf('fr') !== -1)

views/index.pug

@@ -22,6 +22,7 @@ html(lang=locale)
       =_('Soutenez La Quadrature du Net !')
   body
     form(action="./generate.png" target="_blank")
+      input(type="hidden" name="lang" value=locale)
       nav
         a
           img(src="./imgs/logo_lqdn.svg" alt="LQDN")
@@ -106,9 +107,9 @@ html(lang=locale)
               =_('GÉNÉRER')
       main
         div#langPicker
-          button(type="submit" name="lang" value="fr" formaction="" formtarget="_self")#frButton
+          button(type="submit" name="changeLang" value="fr" formaction="" formtarget="_self")#frButton
             =_('Français')
-          button(type="submit" name="lang" value="en" formaction="" formtarget="_self")#enButton
+          button(type="submit" name="changeLang" value="en" formaction="" formtarget="_self")#enButton
             =_('Anglais')
         div
           noscript