Set base for settings, add volatile settings for theme and language

Goal is to have a common and reusable base for the settings. Having nice styles and saving preferences is out of scope for now.

Note the conversation page is now the "main page" instead of the account settings.

Change-Id: I328686047d924642ae6781096c9f57308e8fea22
diff --git a/client/src/locale/en/translation.json b/client/src/locale/en/translation.json
index 6b430f1..c8f05b0 100644
--- a/client/src/locale/en/translation.json
+++ b/client/src/locale/en/translation.json
@@ -30,6 +30,9 @@
   "conversation_title_more": "{{member0}}, {{member1}}, {{member2}}, +{{excess}} other members",
   "dialog_close": "Close",
   "dialog_cancel": "Cancel",
+  "Menu": "Menu",
+  "settings_account": "Account settings",
+  "settings_general": "General settings",
   "logout": "Log out",
   "username_input_helper_text_success": "Username available",
   "username_input_helper_text_taken": "Username already taken",
@@ -72,9 +75,14 @@
   "calling": "Calling {{member0}}",
   "connecting": "Connecting...",
   "end_call": "End call",
+  "incoming_call_medium": "",
   "refuse_call": "Refuse",
   "accept_call_audio": "Accept in audio",
   "accept_call_video": "Accept in video",
+  "settings_title_general": "General",
+  "settings_title_system": "System",
+  "setting_dark_theme": "Dark theme",
+  "setting_language": "Language",
   "login_username_not_found": "Username not found",
   "login_invalid_password": "Incorrect password",
   "login_form_title": "Login",