Make getEntry() and getProperty() work with objects

[gmazzap]

Both functions getEntry() and getProperty() work by now only with arrays (or ArrayAccess instances) but not with object, even if getProperty() make me think of an object field access.

Moreover, both functions are very similar, acually as of now getProperty() is just a subset of getEntry() I think one should be removed. This is a BC break, but being this lib in a zero-point release state, that should not be a problem.

Finally, getProperty() return an unexpected null when given argument is an array, IMO in that case the function should throw an exception instead.

[tomphp]

getProperty() was supposed to work with object properties - it was a copy and paste bug. For the time being I have fixed it in 700ecc8. I will study you PR regarding the other issues.

Indeed, this is a zero-point release, I'm not afraid of BC breaks at this point in time (best to get it right) ;-)