Add custom error message if Twisted is not installed

Fixes #206.

syncplay/messages_de.py

@@ -116,6 +116,7 @@ de = {
     "empty-error": "{} darf nicht leer sein",  # Configuration
     "media-player-error": "Player-Fehler: \"{}\"",  # Error line
     "unable-import-gui-error": "Konnte die GUI-Bibliotheken nicht importieren. PySide muss installiert sein, damit die grafische Oberfläche funktioniert.",
+    "unable-import-twisted-error": "Could not import Twisted. Please install Twisted v12.1.0 or later.", #To do: translate
 
     "arguments-missing-error": "Notwendige Argumente fehlen, siehe --help",
 

syncplay/messages_en.py

@@ -115,6 +115,7 @@ en = {
     "empty-error": "{} can't be empty",  # Configuration
     "media-player-error": "Media player error: \"{}\"",  # Error line
     "unable-import-gui-error": "Could not import GUI libraries. If you do not have PySide installed then you will need to install it for the GUI to work.",
+    "unable-import-twisted-error": "Could not import Twisted. Please install Twisted v12.1.0 or later.",
 
     "arguments-missing-error": "Some necessary arguments are missing, refer to --help",
 

syncplay/messages_it.py

@@ -115,6 +115,7 @@ it = {
     "empty-error": "Il campo {} non può esssere vuoto",  # Configuration
     "media-player-error": "Errore media player: \"{}\"",  # Error line
     "unable-import-gui-error": "Non è possibile importare le librerie di interfaccia grafica. Hai bisogno di PySide per poter utilizzare l'interfaccia grafica.",
+    "unable-import-twisted-error": "Non è possibile importare Twisted. Si prega di installare Twisted v12.1. o superiore.",
 
     "arguments-missing-error": "Alcuni argomenti obbligatori non sono stati trovati. Fai riferimento a --help",
 

syncplay/messages_ru.py

@@ -116,6 +116,7 @@ ru = {
     "empty-error": "{} не может быть пустым.",  # Configuration
     "media-player-error": "Ошибка проигрывателя: \"{}\"",  # Error line
     "unable-import-gui-error": "Невозможно импортировать библиотеки GUI (графического интерфейса). Необходимо установить PySide, иначе графический интерфейс не будет работать.",
+    "unable-import-twisted-error": "Could not import Twisted. Please install Twisted v12.1.0 or later.", #To do: translate
 
     "arguments-missing-error": "Некоторые необходимые аргументы отсутствуют, обратитесь к --help",
 

syncplay/ui/ConfigurationGetter.py

@@ -496,6 +496,11 @@ class ConfigurationGetter(object):
                     import appnope
                     appnope.nope()
             except ImportError:
+                try:
+                    from twisted.trial import unittest
+                except:
+                    print(getMessage("unable-import-twisted-error"))
+                    sys.exit()
                 print(getMessage("unable-import-gui-error"))
                 self._config['noGui'] = True
         if self._config['file'] and self._config['file'][:2] == "--":