Fixed a bug of HashIterator

The old implementation of HashIterator can't support `"\0"` prefix key.
I think the array and the object is different. Maybe the user didn't
want to get the private property of an object. but in an array, `"\0"`
prefix key doesn't mean private key. so we should return `"\0"` prefix
key when it is an array.
Fix typo
Merge remote-tracking branch 'upstream/master'
Fixed compatibility issue with VS2013
Update objectimpl.h
Value objects allocated with a const char * that is set to null, will not create NULL php values
fixed conflict
when value properties that start with a null byte are set or retrieved (this happens when the user relies on specific Zend features) we now block such access because we do not want the user to be exposed to the peculiarities of the Zend engine
Merge pull request #128 from andot/vs2013

 Fixed compatibility issue with VS2013
updated makefile so that we now also create a static phpcpp library (this in response to pull request #125)
updated Makefile to create output dirs first
Made Type::Null the default type on ByVal and ByRef as this will allow any type (aka no type hinting)
Use specified php-config for linker/compiler flags rather than the system default.
Merge pull request #135 from alanevans/master

Use specified php-config for linker/compiler flags rather than the system default. Fixes CopernicaMarketingSoftware/PHP-CPP#134
Fixed a tiny typo in the readme
use emplace_back instead of push_back for creating the vector of values
emplace_back does not work, since some types cannot be constructed directly from a Php::Value
Allow casting a Php::Value to a std::set
Respect the CXX and AR env variables.
One advantage of this small change is that during cross-compilation you do not need to adjust the Makefile.
Better clean-up.