Add im7 core GetDelegates() and GetFeatures()

[coderkun]

ImageMagick provides a function to list all registered delegates and a second function to list built-in features. Both are very useful for applications to know the capabilities of ImageMagick and to verify an ImageMagick installation.

This Pull Request adds the function GetDelegates() which returns the output of GetMagickDelegates() and the function GetFeatures() which returns the output of GetMagickFeatures().