Properly set the method bitfield in function name symbol

   Methods declared outside class definition block were having the method
bit incorrectly set, what could cause an error or assertion.
Correct a missing check for enough bytes when printing a float number

  All other cases did properly pass the correct argument, but for
floats it could check for less bytes, and write past the end of the
buffer when adjusting the format width.
Add a new NeHe tutorial.

  This has been translated from the windows C++ source example.