[WIP]: Update Reflection component to v2

Part of the operation for speeding phpDocumentor up is removing the extra step of putting the parsed contents in Descriptors using Reflection objects. Instead Descriptors will be assembled directly from the parsed contents.

In this PR I have removed all descriptors as they have been moved to the Reflection Component and changed all files to match the updated API for the Descriptors.

In addition to this the minimum PHP version is updated to 5.4 to match the new Reflection component
Just to be sure about order of operation here... the `!` will apply to the entire `instanceof` expression, and not just apply to the return of `$class->getParent()`?  My imagination could see `!$class->getParent()` becoming `true` or `false`, and thus the final expression being `true instanceof DescriptorAbstract` and thus always taking the ternary's ELSE path.  Since neither path is an error path, it would be easy for a bug to slip through right here, if I'm right about the order of operation at execution.