fixed a bug with debug text entry
bug: launching first instance of level would make debug menu behave as expected
however, closing this and then launching another instance of level would incorrectly parse underscore input, because of a bug (?) in pygame's keydown events (which parses '-' instead of '_').
this is a workaround; pygame correctly parses shift-key text inputs in their TextInput event, and in truth, it's more accurate and makes more sense to read TextInput events as, well, text inputs to the debug menu