v0.18

• added more unicode helper classes and functions:
  • Unicode Filter class
  • diacriticsfilter()
  • Unicode Normalizer.
• small fix in Configuration Class
• Bumped library version to 4.0
• more tests added to make check.
• overhauled autoconfigure stuff.
  • MacOSX is now better supported.
  • libzlib, libbz2 and libtar ar no longer optional