Added referenced counted shared pointer class

[marcuschangarm]

Class follows the shared_ptr API from C++11. Reference counts are updated when SharedPointer objects are passed around by value.

Usage:

class A;

SharedPointer<A> objectFactory()
{
    SharedPointer<A> result;

    result = SharedPointer<A>(new A(...));

    return result;
}

...

SharedPointer<A> object1;
SharedPointer<A> object2;

// assignment
object1 = objectFactory();
object2 = object1;

// invoke method in object pointed to
object1->doStuffWithObject();

// invoke method in container
object1.use_count();

[marcuschangarm]

@bogdanm I've added the changes you mentioned last time we spoke about this.

[marcuschangarm]

see https://github.com/ARMmbed/core-util/pull/30

[hugovincent]

Sorry if you've already discussed this but if it follows the std::shared_ptr API why not call it mbed:: shared_ptr or something?

[marcuschangarm]

I wanted to make it clear it is not the same thing. The constructor is different for example.

And the name resembles FunctionPointer.

[hugovincent]

Ah ok, similar but not the same API then.