Add new i18n languages and update existent ones

- Add 21 new languages where the UI was translated (all translations
  are 100% complete except for Chinese Simplified (96%)
  and Amharic (37%)).
- Update some translations for preexistent languages.

Change-Id: I64be0a2dd551c12af1547a616b4f49f97c471bde
diff --git a/src/_locales/sl/messages.json b/src/_locales/sl/messages.json
new file mode 100644
index 0000000..752779a
--- /dev/null
+++ b/src/_locales/sl/messages.json
@@ -0,0 +1,114 @@
+{
+	"appName": {
+		"message": "Prevedi izbrano besedilo",
+		"description": "The app name"
+	},
+	"appBetaName": {
+		"message": "Prevedi izbrano besedilo (Beta)",
+		"description": "The beta app name"
+	},
+	"appDescription": {
+		"message": "Prevedi izbrano besedilo z Google Prevajalnikom",
+		"description": "The app description"
+	},
+	"contextmenu_title": {
+		"message": "Prevedi izbrano v...",
+		"description": "Title of the context menu that appears when a right click is done. Inside this parent menu there are the menus"
+	},
+	"contextmenu_title2": {
+		"message": "Prevedi izbrano v '$language$'",
+		"description": "Title of the context menu that appears when a right click is done and there's only one language available.",
+		"placeholders": {
+			"language": {
+				"content": "$1",
+				"example": "Language to translate into."
+			}
+		}
+	},
+	"contextmenu_edit": {
+		"message": "Urejajte jezike...",
+		"description": "Title of the option inside the 'Translate section into...' context menu."
+	},
+	"options_welcome": {
+		"message": "Dobrodošli!",
+		"description": "Title of the options page"
+	},
+	"options_introduction": {
+		"message": "Prosimo, izberite jezike, za katere želite, da se pokažejo v meniju \"prevedi\".",
+		"description": "Introduction paragraph to the options pages"
+	},
+	"options_languageselectheader": {
+		"message": "Jeziki:",
+		"description": "Header of the language select option."
+	},
+	"options_otheroptionsheader": {
+		"message": "Druge možnosti:",
+		"description": "Header of the options page."
+	},
+	"options_tabsoption_1": {
+		"message": "Za vsak prevod odpri Google Prevajalnik v novem zavihku.",
+		"description": "Option which defines how should the app behave in relation to tabs."
+	},
+	"options_tabsoption_2": {
+		"message": "Odpri Google Prevajalnik v lastnem zavihku in prikaži samo zadnji prevod, namesto odpiranja več zavihkov.",
+		"description": "Option which defines how should the app behave in relation to tabs."
+	},
+	"options_tabsoption_3": {
+		"message": "Odpri Google prevajalnik na plošči (aktivirati morate zastavo <a href='chrome://flags/#enable-panels' id='panelsflag'>--enable-panels</a>). <sup style='color:red; font-weight: bold;'>EKSPERIMENTALNO</sup>",
+		"description": "Option which defines how should the app behave in relation to tabs."
+	},
+	"options_savebutton": {
+		"message": "Shrani",
+		"description": "Save button in the settings page"
+	},
+	"options_addlanguage": {
+		"message": "Dodaj jezik",
+		"description": "Title for the 'Add language' dialog"
+	},
+	"options_addlanguage_addbutton": {
+		"message": "Dodaj",
+		"description": "Add button in the footer of the languages list"
+	},
+	"options_language_label": {
+		"message": "Jezik:",
+		"description": "Label for the language selector in the 'Add language' dialog"
+	},
+	"options_credits": {
+		"message": "Zasluge",
+		"description": "Title for the credits link and dialog"
+	},
+	"options_credits_homepage": {
+		"message": "domača stran",
+		"description": "Homepage link for an item in the credits. NOTE: put in in lowercase letters"
+	},
+	"options_credits_by": {
+		"message": "avtorja/ice",
+		"description": "Fragment of the author statement in an item of the credits. NOTE: put in in lowercase letters. EXAMPLE: '{{options_credits_by}} Adrià Vilanova Martínez'"
+	},
+	"options_ok": {
+		"message": "V redu",
+		"description": "OK button in the dialogs"
+	},
+	"options_cancel": {
+		"message": "Prekliči",
+		"description": "Cancel button in the dialogs"
+	},
+	"notification_install_title": {
+		"message": "Hvala, ker ste namestili 'Translate Selected Text'"
+	},
+	"notification_install_message": {
+		"message": "Kliknite to obvestilo, da jo nastavite."
+	},
+	"notification_upgradedtostorage_title": {
+		"message": "'Translate Selected Text' je bil posodobljen na različico 0.6!"
+	},
+	"notification_upgradedtostorage_message": {
+		"message": "Zdaj bodo vaše možnosti enake na vseh vaših napravah! Slabost tega je, da morate žal to razširitev ponovno nastaviti :-( Kliknite to obvestilo, da jo nastavite."
+	},
+	"notification_reorder_title": {
+		"message": "'Translate Selected Text' je bil posodobljen na različico 0.7!"
+	},
+	"notification_reorder_message": {
+		"message": "Zdaj lahko nastavite, v kakšnem zaporedju naj se jeziki pojavijo v kontekstnem meniju. "
+	}
+}