Language: Remove logic for class file inclusion

Language: Remove logic for class file inclusion

* Remove strcspn() check in newFromCode already in isValidCode().
* Leverage the autoloader instead via class_exists instead of
  including files based on user input.
* Create fallback instance directly instead of recursing back
  into newFromCode().

* Remove method preloadLanguageClass (unused).
* Remove method getClassFileName (unused)

Change-Id: I90035ca4b07facae051b1a584e92df72b42c4a49