Rewritten class loader to skip deprecated class files:

- Rewritten class loader to skip deprecated class files which should make all
  applications working again. This is done by checking its size because I
  will remove all code from the PHP include file and add a @DEPRECATED tag to
  it. A typical size is 24 bytes
- __set() and __get() are now calling debugBackTrace() with a message to aid
  finding e.g. typos in field/attribute names
- debugBackTrace() does now accept an optional parameter for a message
- TODOs.txt updated