Improve/fix pluginmanager.py

The pluginmanager.py has some things to fix, for example:

  • “Press any key to exit…” only works with enter
  • if you don’t specify path to yarn.lock (or set it to “”) you will get message saying that a file was not copied but the file name is not in the message
  • An exception is thrown while deleting the “implementations” folder if the folder does not exist