Began optimized re-write: improved read() and read_nested()

CHANGES

 - read() is fully functional and reads non-nested INI files. Full
   optimized rewrite.
 - read_nested() is fully functional and reads nested INI files. Partly
   rewritten.
 - Package mechanism has changed: dump objects, return a plain table
   with read() and read_nested() functions

TODO

 - Implement write() and write_nested()
 - Update documentation
implemented write(), write_nested(). FIXME: read_nested()
read(): ignore empty lines
read_nested() fixed. FIXME: write_nested()
read_nested(): disallow anonymous closings

This fixes all known bugs.
Update README and LICENSE for new stable version 2