Add comments for translators (#9510)

* Add translator comments for "special" strings

* Add translator comments for some "tricky" strings

src/client/fontengine.cpp

@@ -194,6 +194,14 @@ void FontEngine::readSettings()
 		m_default_size[FM_Fallback] = m_settings->getU16("fallback_font_size");
 		m_default_size[FM_Mono]     = m_settings->getU16("mono_font_size");
 
+		/*~ DO NOT TRANSLATE THIS LITERALLY!
+		This is a special string. Put either "no" or "yes"
+		into the translation field (literally).
+		Choose "yes" if the language requires use of the fallback
+		font, "no" otherwise.
+		The fallback font is (normally) required for languages with
+		non-Latin script, like Chinese.
+		When in doubt, test your translation. */
 		m_currentMode = is_yes(gettext("needs_fallback_font")) ?
 				FM_Fallback : FM_Standard;
 

src/client/game.cpp

@@ -4184,6 +4184,7 @@ void Game::showPauseMenu()
 				<< strgettext("- Creative Mode: ") << creative << "\n";
 		if (!simple_singleplayer_mode) {
 			const std::string &pvp = g_settings->getBool("enable_pvp") ? on : off;
+			//~ PvP = Player versus Player
 			os << strgettext("- PvP: ") << pvp << "\n"
 					<< strgettext("- Public: ") << announced << "\n";
 			std::string server_name = g_settings->get("server_name");

src/client/keycode.cpp

@@ -109,6 +109,7 @@ static const struct table_key table[] = {
 	DEFINEKEY1(KEY_RETURN, N_("Return"))
 	DEFINEKEY1(KEY_SHIFT, N_("Shift"))
 	DEFINEKEY1(KEY_CONTROL, N_("Control"))
+	//~ Key name, common on Windows keyboards
 	DEFINEKEY1(KEY_MENU, N_("Menu"))
 	DEFINEKEY1(KEY_PAUSE, N_("Pause"))
 	DEFINEKEY1(KEY_CAPITAL, N_("Caps Lock"))
@@ -121,7 +122,9 @@ static const struct table_key table[] = {
 	DEFINEKEY1(KEY_UP, N_("Up"))
 	DEFINEKEY1(KEY_RIGHT, N_("Right"))
 	DEFINEKEY1(KEY_DOWN, N_("Down"))
+	//~ Key name
 	DEFINEKEY1(KEY_SELECT, N_("Select"))
+	//~ "Print screen" key
 	DEFINEKEY1(KEY_PRINT, N_("Print"))
 	DEFINEKEY1(KEY_EXECUT, N_("Execute"))
 	DEFINEKEY1(KEY_SNAPSHOT, N_("Snapshot"))