added hashiterator, this is going to be one of the implementation classes for the upcoming value iterator
moved implementation for hashiterator to header file, introduced invaliditerator class, valueiterator now uses the hashiterator class internally
removed unique_ptr because client applications do not allow unique_ptr with unknown types
added missing methods to the hashiterator class
Small improvements
Regained the ability to run the tests (script tests/test.sh) with option -m (Valgrind)
added option -q (Quiet)
Full range of options, see $ ./test.sh -h
Some other improvements (see diff)
Merge pull request #49 from valmat/small-improvements

Small improvements
implementation of traverseiterator (untested)
fixed some issues with traverse iterators
first key/value pair was not correctly retrieved, this has now been fixed
update documentation about iterating
Merge branch 'master' of https://github.com/CopernicaMarketingSoftware/PHP-CPP
documentation update
fixed compile problem with php 5.5
fixed iterator for php 5.5
test was broken, real output was correct, expected output was wrong
fixed crashes for certain test cases on php 5.3
implemented php output streams as was asked for in issue #51
errors have a limited buffer, and discard any overflow data, replaced std::cout calls with Php::out calls in the documentation
added echo() function requested in issue #51
update documentation