Player component now remembers previously set volume

Updated name of updatePlaylist->updatePlaylistFiles for clarity and added updatePlaylist route

Added smarter safe download override, will auto activate if subtitle args are included.

backend/config.js

@@ -155,6 +155,13 @@ function setConfigItems(items) {
     return success;
 }
 
+function globalArgsRequiresSafeDownload() {
+    const globalArgs = config_api.getConfigItem('ytdl_custom_args');
+    const argsThatRequireSafeDownload = ['--write-sub', '--write-srt'];
+    const failedArgs = globalArgs.filter(arg => argsThatRequireSafeDownload.includes(arg));
+    return failedArgs && failedArgs.length > 0;
+}
+
 module.exports = {
     getConfigItem: getConfigItem,
     setConfigItem: setConfigItem,
@@ -164,7 +171,8 @@ module.exports = {
     configExistsCheck: configExistsCheck,
     CONFIG_ITEMS: CONFIG_ITEMS,
     initialize: initialize,
-    descriptors: {}
+    descriptors: {},
+    globalArgsRequiresSafeDownload: globalArgsRequiresSafeDownload
 }
 
 DEFAULT_CONFIG = {