Accessible modals (#560)

Improve the accessibility of our modals (the color picker and the export dialog)

Implement a focus trap so that tapping through the controls inside them don't escape to outer elements, it also allows to close the modals with the "Escape" key.

public/locales/es/translation.json

@@ -35,7 +35,10 @@
     "extraBold": "Extra Grueso",
     "architect": "Arquitecto",
     "artist": "Artista",
-    "cartoonist": "Caricatura"
+    "cartoonist": "Caricatura",
+    "fileTitle": "Título del archivo",
+    "colorPicker": "Selector de color",
+    "canvasBackground": "Fondo del lienzo"
   },
   "buttons": {
     "clearReset": "Limpiar lienzo y reiniciar el color de fondo",
@@ -44,7 +47,9 @@
     "copyToClipboard": "Copiar al portapapeles",
     "save": "Guardar",
     "load": "Cargar",
-    "getShareableLink": "Obtener enlace para compartir"
+    "getShareableLink": "Obtener enlace para compartir",
+    "showExportDialog": "Mostrar diálogo para exportar",
+    "close": "Cerrar"
   },
   "alerts": {
     "clearReset": "Esto limpiará todo el lienzo. Estás seguro?",